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Degenhart, A. Stabilization of a brain—computer interface via the alignment of low-dimensional spaces of neural activity. Download references. We thank participant T5 and his caregivers for their dedicated contributions to this research, N. Lam, E. Siauciunas and B. Davis for administrative support and E. Woodrum for the drawings in Figs. Garlick; S.
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. Francis R. Willett, Donald T. You can also search for this author in PubMed Google Scholar. All authors reviewed and edited the manuscript. Correspondence to Francis R. All other authors have no competing interests.
Peer review information Nature thanks Karim Oweiss and the other, anonymous, reviewer s for their contribution to the peer review of this work. Peer reviewer reports are available. The y t vectors describe the probability of each character being written at that moment in time, and the z t scalars go high whenever the RNN detects that T5 is beginning to write any new character. Note that the top RNN layer runs at a slower frequency than the bottom layer, which we found improved the speed of training by making it easier to hold information in memory for long time periods.
Thus, the RNN outputs are updated only once every ms. Also, note that we used a day-specific affine transform to account for day-to-day changes in the neural activity bottom row —this helps the RNN to account for changes in neural tuning caused by electrode array micromotion or brain plasticity when training data are combined across multiple days.
First, single-letter and sentences training data are collected blue and red blocks. Finally, the RNN is held fixed and evaluated green blocks. First, the single-letter data are time-warped and averaged to create spatiotemporal templates of neural activity for each character. These templates are used to initialize the hidden Markov models HMMs for sentence labelling. After labelling, the observed data are cut apart and rearranged into new sequences of characters to make synthetic sentences.
Finally, the synthetic sentences are combined with the real sentences to train the RNN. The HMM states correspond to the sequence of characters in the sentence. The HMM-identified character start times form clear hotspots on the heat maps. Data are shown from a grid search over both parameters, and lines show performance at the best value for the other parameter. Results indicate that both parameters are needed for high performance, even when the other is at the best value.
Using synthetic data is more important when the size of the dataset is highly limited, as is the case when training on only a single day of data blue line.
Note that the inputs given to the RNN were z -scored, so the input white noise is in units of standard deviations of the input features. This is because feature means change slowly over time. For each parameter setting, three separate RNNs were trained circles ; results show low variability across RNN training runs.
Each circle shows the performance on one of seven days. As shown in the table, all parameters show a statistically significant improvement for at least one condition CIs do not intersect zero. Each session is labelled according to the number of days passed relative to 9 December day 4. Results show that although patterns of neural activity clearly change over time, their essential structure is largely conserved as decoders trained on past days transfer readily to future days.
High values indicate a high similarity in how characters are neurally encoded across days. The fact that correlations are higher in the anchor space suggests that the structure of the neural patterns stays largely the same as it slowly rotates into a new space, causing shrinkage in the original space but little change in structure. Each circle represents the neural activity pattern for a single character, and each x symbol shows that same character on a later day lines connect matching characters.
The relative positioning of the neural patterns remains similar across days, but most conditions shrink noticeably towards the origin. This is consistent with the neural representations slowly rotating out of the original space into a new space, and suggests that scaling-up the input features may help a decoder to transfer more accurately to a future session by counteracting this shrinkage effect.
All session pairs X, Y were considered. Decoders were first initialized using all data from session X and earlier, then evaluated on session Y under different input-scaling factors for example, an input scale of 1. Results show that when long periods of time pass between sessions, input scaling improves performance.
We therefore used an input-scaling factor of 1. On the left, example noise vectors are plotted each line depicts a single example. Noise vectors are shown for all time steps of neuron 1. The first time steps describe the noise of neuron 1 and the last time steps describe the noise of neuron 2. The diagonal band creates noise that is temporally correlated within each simulated neuron but the two neurons are uncorrelated with each other.
Even in the presence of temporally correlated noise, the time-varying trajectories are still much easier to classify.
Unlike the temporally correlated noise, this covariance matrix generates spatiotemporal noise that has correlations between time steps and neurons. Again, time-varying trajectories are easier to classify than constant trajectories.
See Supplementary Note 1 for a detailed interpretation of this figure. Each circle represents a single movement and bar heights show the mean. Results confirm that the optimized alphabet is indeed easier to classify than the Latin alphabet, and that the Latin alphabet is much easier to classify than straight lines, even when the lines have been optimized. The distance matrices were sorted into seven clusters using single-linkage hierarchical clustering. The distance matrix for the optimized alphabet has no apparent structure; by contrast, the Latin alphabet has two large clusters of similar letters letters that begin with a counter-clockwise curl, and letters that begin with a downstroke.
Microelectrode array locations blue squares were determined by co-registration of postoperative CT images with preoperative MRI images. Each rectangular panel corresponds to a single electrode and each blue trace is a single spike waveform 2.
On this day, 92 electrodes out of had a threshold crossing rate of at least 2 Hz. In this video, participant T5 copies sentences displayed on a computer monitor with the handwriting-brain computer interface. When the red square on the monitor turns green, this cues T5 to begin copying the sentence. Participant T5 is paralyzed from the neck down C4 ASIA C spinal cord injury and only generates small micromotions of the hand when attempting to handwrite. T5 retains no useful hand function.
In this video, participant T5 answers questions that appear on a computer monitor using the handwriting brain-computer interface. T5 was instructed to take as much time as he wanted to formulate an answer, and then to write it as quickly as possible. In a prior study Pandarinath et al. Here, we show an example sentence typed by T5 using the point-and-click system shown on the bottom and the new handwriting brain-computer interface shown on the top , which is more than twice as fast.
Reprints and Permissions. High-performance brain-to-text communication via handwriting. Download citation. Received : 02 July Accepted : 26 March Published : 12 May Issue Date : 13 May Anyone you share the following link with will be able to read this content:.
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If you catch a small fish, throw it There are no spirits in the water which will punish you. Small fish should be allowed to grow and reproduce. If fish are caught before they are fully grown, there will be less fish to reproduce for the future. Handling house lzards with bare hands causes warts kulogo. This has no scientific basis, Warts are caused by viruses. Check your initial answers with the explanations given in Column B.
No scientific basis How well did you score in this activity? If your score Is at least 9, it shows that you possess an analytical and scientific mind, SUMMARY This unit introduced you to what science and technology are all about. The work of some scientists, especially those of Filipino scientists, certainly gave you something to be proud of.
Scientists think critically; they also have positive attitudes that are attributed to their success in their scientific endeavors. You too can think and act like a scientist. You just have to practice the basic skills in observing, measuring, classifying, making inferences, and interpreting data. Mastery of these skills is important for coping with daily life. Acquisition of these skills is important for making decisions.
It has been shown that science and technology are complementary. They affect the development of society in general. They can help people regardless of their needs, abilities, or interests.
However, each one has to be careful in selecting what technology to use for a specific situation and to learn how to dispose of them to prevent danger to life, property, and the environment.
Column A Column B 1. Open-ended or Constructed - Response Items Inside the box is a list of waste materials. Group them in three ways. Give the basis for each grouping. Give a possible reason for the differences. Study the graph at the right Is the air temperature decreasing all the way from the ground to 80 the upper atmosphere? Whats the air temperature near the ground? Atwhat height is the lowest air temperature recorded?
The 0 7 highest air temperature? She is worried that she might fail in the test because she has been absent for two days the past week.
Her friend told her not to worry but to eat fish and peanuts the night before the test because these are brain foods. She followed the advice of her friend, slept and went to school the following day. Do you think the advice of Mila's friend became helpful? Clue: Nutrients are for all body parts. Do you think Mila passed the test? If you were Mila, what would you have done to make sure that you pass the test? Do science and technology benefit you? Cite an example.
Do science and technology affect you negatively? They use special methods to determine truths about things happening around. They gather facts and use these as clues, not answers, to scientific mysteries. They look at many relevant facts as they can and propose explanations for the events they observe.
They conduct experiments to test their explanations. From the results of the experiments, scientists develop a theory—a powerful and time-tested concept that makes useful and dependable predictions about the natural world. A theory is tested over and over again. When it survives the tests, it is presented to the scientific community. A theory may or may not be accepted outright. It may change after additional tests are made. And finally, if accepted as true by the scientific community, the theory becomes a law.
But scientific laws are still scrutinized and may be changed as new data arise. In short, experimentation is the heart of science. In this unit, you will be exposed to the different steps conducting experiments or scientific investigations.
Your findings may not become a law but you will experience the way scientists think and do their work. Goodyear accidentally discovered rubber. Wiliam Perkins , English chemist discovered a synthetic dye by chance while looking for other things. This method of finding something else of value by chance is called serendipity. One case of serendipity occurred in the research laboratory of a company that produces sticky tape.
In the s, some researchers found a new bonding agent but decided that it was worthless since it could not stick a paper tightly to a surface. This failure was later on converted into a successful product, Post-it notepads. Most scientists however, follow the experimental method of solving problems. You will leam more of this in Lesson 2. What are their other contributions to science and technology besides those already mentioned? Give one disadvantage. Explain your answer briefly.
They ask questions about the phenomenon or situation observed. They carefully observe and look for regularities in their observations. They are able to synthesize observations and make good inferences. Only investigators with trained scientific minds could chance upon such findings. The answer to this question may vary with the situation. The important thing is for people to observe keenly and ask the right question at the right time. You must have noticed that many people accept as truth what they see, hear, or read.
They make conclusions solely based on that information and without verifying the source of that information. More often than not, this attitude gives rise to misunderstanding and problems. Asking the right questions at the right time is a sign of curiosity, objectivity, and a desire to learn more. Asking the right questions could reduce bias, anxiety, or even panic. The rule to follow is: If you are not sure about anything, ask. Activity 2. Form a group with about five members each.
A smaller group will allow members to participate more actively in the discussion. Read the situations below. Choose one for your group to brainstorm on and answer questions a to d.
What questions come to your mind when you read the situation? How will you find out answers to these questions? Why did you choose that method of finding out the answer to your questions?
Could these problems be prevented? Situation 1: Yesterday was your town fiesta. You visited several houses. You were served lots of food. That night you had stomach ache and started vomiting, Situation 2: You have seen the commercial on shampoo endorsed by your favorite actress. Her hair looks beautiful. You tried the shampoo yourself. After one week, you observed you have lots of falling hair. Situation 4: The fish catch in the lake is dwindling.
Listen to the presentation of the other groups. Compare your method with their methods. Are there similarities in the methods used? What are different? Why is it the best way than the other methods presented? Some questions or problems may have several answers. Other questions are opinion based, that there are no right or wrong answers. But, when giving an opinion, it is important that you have a sound basis for it.
Home Activity Write a short essay on one of your most unforgettable experiences or problems. Narrate how you arrived at your answer.
Do you think that method was the best? Lesson 2. Doing experiments or conducting scientific investigations enabled them to see cause-effect relationships. The experimental method involves several steps. Galileo Galilei , Italian astronomer and physicist used this method when he discovered the principle of the pendulum. Joseph Priestly , English clergyman and chemist identified the gas, carbon dioxide, using the same method.
Read about these discoveries at your own time. What are the basic steps of the experimental method of investigation? How do we go about doing these steps?
Identify or define the problem. What problem or issue do you want to work on? Is the problem clear and specific? Is the solution to this problem attainable? For example, Dario's problem in Unit 1 , was finding out how he could make an herbal preparation that would stay long in contact with the wound. Was a possible solution in sight? If you are not sure what you would like to do, consult a local professional or read more about the problem.
Gather enough information and study them. What has been achieved so far in relation to the problem? Are the given facts relevant and measurable? Get only relevant information about the problem. When organized, the information may reveal some patterns, regularities, or trends that will establish relationships among given facts.
Pattems and trends help in making hypotheses. Formulate the hypothesis. Think about what might happen in response to certain inputs or assumptions.
A hypothesis is an educated guess and must be based on information from past researches or literature studies. Dario's hypotheses were: a. Essentially, the hypothesis provides the ground or justification for conducting specific studies and guides the investigator in the course of his or her study.
Before a hypothesis can be accepted as a fact, it has to be proven first through experimentation and the findings have to be supported by more than one testing to erase any doubts of a chance success. Test the hypothesis. These factors are known as variables. Two types of variables are considered: those that can be controlled and those that can be changed or manipulated. The variable that is changed or that changes is called the independent variable while the variable that responds to the change is called the dependent variable.
Remember the rule: Vary only one variable or factor at a time while keeping all other factors in the experiment unchanged or constant. In an experiment, a control setup is used as reference or standard against which the results of the experimental setups will be compared. Note that testing or experimenting is done under controlled conditions preferably indoors where temperature can be regulated at will , although this is not possible when conducting field studies.
Wherever you are doing your investigation, observations should be done closely to see if any relationship exists between and among sets of collected data. Establishing relationships is essential in the experimental method. Make a conclusion. All collected data are clearly analyzed and correctly interpreted. This analysis helps any investigator decide whether to accept or reject his or her hypothesis. From this, a conclusion or a general statement can be made about the study.
Verify the conclusion. To make sure that the findings are conclusive, repeat the experiment using the same procedure and conditions. If the results are almost the same, the conclusion is What are the important parts of a science investigation? Do Activity He thought that bees could distinguish one kind of flower from another. He suspected that the bees could distinguish flowers by color. To determine if this was true, he designed a set of simple experiments.
He first trained bees to come to a source of honey located on a piece of blue card. The bees made many trips between their hives and the source of food on the blue card. The bees returned to the blue card and avoided the red card.
The bees were able to distinguish the blue card from the red card. After von Frisch published his results, other scientists designed similar experiments. Their findings supported von Frisch's hypothesis, 2. The next activity will guide you, Lesson 2. For example, you observe that the flagpole casts a shadow. Some hours of the day, the shadow is long; other times, it is short.
What questions come to your mind? What questions can be investigated, given your educational background and limited resources? Did you ask a question about what might affect the length of the shadow?
Either problem is specific and measurable. The seven short activities that follow will guide you in the process of investigation. Study the object or situation assigned to your group or one you chose to study. Individually, write three questions about the object or situation in 5 minutes, 3. Discuss your questions within the group. Try to answer each question. What questions were easy to answer? Why were you able to answer them easily?
Why can you not answer the other questions easily? Which question can you investigate, given limited time, resources, and science background? Asa group, state the specific problem that you want to investigate. These questions do not require much thinking. High-level questions, on the other hand, require you to think about why and how things happen. Furthermore, you need to think of possible answers to the question formulate hypotheses , test one hypothesis at a time to determine cause-effect relationship, and make conclusions based on the data gathered.
Go back to the problem about shadows. Do you think there is a relationship between the position of the sun in the sky and the length of an object's shadow?
You can also state your hypothesis in different ways, for as long as the factors involved in the study are included in the statement. Study the problem identified by your group in Activity 2.
Does your hypothesis state the relationship between the factors involved in the study? Does the hypothesis give a tentative answer to the problem or question? As a group, decide on one hypothesis that will give you an idea what might happen in response to certain inputs that you will do in the next activity. Show your hypothesis to the teacher before doing Activity 2. Now, you are ready to design a procedure to test your hypothesis. Again, go back to the hypothesis about shadows. Think of what might affect the shadow—the position of the sun at different hours of the day, the brightness of the surrounding, the position of the flagpole in relation to the sun, the height of the flagpole, and the time when the observation and measurement are made.
The position of the sun the variable that changes is the independent variable while the length of the shadow the variable that responds to the change is the dependent variable. What variables should be kept the same in order to have a fair test? Apart from the independent variable, all the other variables should be kept the same. In this way, you will be able to say that any change in an object's shadow must have been caused by the change in the position of the sun.
Remember that the success of any scientific investigation depends largely on the scientist's ability to control variables.
Also, remember that the independent variable must be given values. For example, the position of the sun can be observed at different hours of the day: 9 a.
The dependent variable or the length of an object's shadow must be measured using a standard instrument e. From your hypothesis in Activity 2. Identify the following: a. Give values for your independent variable. Tell what instrument you will use to measure the dependent variable, 5. Write down the whole procedure for the experiment.
Assuming that you have gathered the data, how will you show what happened in your experiment? Results of data collection are best recorded in table form. TA p. The shadow gets shorter at noon when the sunrays seem to reach the ground almost perpendicularly.
Time of day Figure 2. These observations can then be explained using Earth's rotation on its axis. Figure 2. Give a possible reason for each observation A, B, and C. If you repeat the activity on shadows another day, you may get slightly different results but the same pattern can be observed. Why do you say so? Complete your investigation by doing the next activity. Follow the procedure described in your design Activity 2. Record your data in a table. Measure up to the tenth value.
Graph your data. Make sure you put the independent variable and the dependent variable in its right place in the graph. Study the graph. Is there a pattern in your results? Describe the pattern.
What do you think the results tell you? Are there any surprises in your results? What do you know now that you didn't know before you started the experiment? What have you leamed from your investigation? List down problems you encountered while conducting your experiment. Make recommendations so that others who may want to do a similar experiment will not meet the same problems. To get meaning out of the data you collected, look back at your original prediction or hypothesis to see whether or not the evidence supports it.
Then try to explain the relationship between the independent variable what was changed and dependent variables what responded to the change and were measured. You might even have to go back to the activity to make further observations when trying to explain results. Was your test fair? The shadow experiment was a fair test because all variabies, except one, were controlled. Also, data collection was done at specific times. Furthermore, the same measuring instrument was used to determine the length of the shadow.
Which test is fair? Give a reason for your choice. She put the same kind and amount of soil in six pots of the same size. She planted the same kind of seedlings into each pot.
The seedlings were of equal age and heights at the time they were planted. She placed all pots in a sunny place in their backyard. Then she watered each pot everyday with different amounts of water. Test 2: Mario wanted to classify water samples from different sources as hard or soft.
He chose bottles of the same sizes and placed equal amounts of water in each bottle. If you can identify the variables in your study, this will help you design the procedure of your investigations as well as interpret the results later. Review these steps using the following problem, Problem: Does alum dissolve faster in hot water? Hypothesis: Alum will dissolve faster in hot water. Without looking at Column 3 try to answer the questions in Column 2.
Table 2. Then, twill show the graph the tabulated data. The speed of alum dissolution became faster terns in pattern? Use as guide the questions in Column 2 of table 2.
Be ready to discuss the results of your Lesson 2. In Astronomy, Geology, or Meteorology, the luxury of performing experiments is limited. Moreover, these sciences usually deal with great magnitudes of time—thousands to billions of years—as those used in geologic time scale.
Nevertheless, the experimental method is stil applicable. Scientists use observation skills to arrive at a logical conclusion, which later can become a theory, and then a law.
How are these observations done? For example, how did Aristotle B. He observed lunar eclipses! During one lunar eclipse, Aristotle saw that the Earth cast a shadow onto the surface of the moon.
He hypothesized that the Earth must be round because its shadow looked like an arc of a circle. He predicted that any and all future lunar eclipses would show the Earth's shadow to be curved regardless of its orientation. Aristotle's prediction has yet to be proven wrong. His reasoning formed the basis for all scientific inquiry today.
He was not the first to argue that the Earth was round but he was the first to offer proof using the lunar eclipse method. He used scientific inquiry in formulating his theory about the Earth. He followed the following steps. He first made an observation. Then he formulated a hypothesis to explain his observation. Lastly, he tested his hypothesis by making a prediction that could be confirmed by further observations.
Home Activity You know what a rainbow is. But have you seen enough rainbows that you can make a general statement about when rainbows appear? If not, do more observations the next time you see rainbows. How do you know that your science investigation was done properly and reported correctly? To grade your project objectively, rubrics or scoring key is used. Rubrics are matrices that define what are expected in a leaming situation.
Rubrics describe the level of performance for each aspect of the investigation and the criteria for each level. These are the criteria that your teacher will use in rating your outputs.
These are also similar to the criteria used by judges when rating your science projects in a science fair. It is good to know the criteria for scoring your outputs so that you will be guided on the important aspects of the investigation or research, Table 2.
There are different rubrics or scoring criteria for different outputs. The next activity gives you experience on rating scientific investigation of others. Then you will be able to use the same rubrics for evaluating your own output. Read the report below. Use the rubric and give each aspect of the report a score. Total your score and give a final rating. Effect of Phosphate-Containing Detergents on Growth of Algae Overview The purpose of this project is 10 determine whether or not phosphates affect the growth of algae as might be found in lakes and streams.
These could reach streams and lakes via runoff from homes and drainage pipes. If these affect algal growth, such runoff needs to be controlled. Hypothesis Phosphates such as those coming from detergents contribute to algal growth. More algae will grow with higher amounts of phosphates in water. Sample algae from the lake was collected and placed in a small open-mouthed container. It was gently stied so as to break up major clumps. This is the starter culture 2. Detergent containing phosphate solution was prepared by putting 2 grams of detergent in 20 mL water.
This is the control setup, 2. It was prepared by mixing one part of phosphate solution in nine parts distilled water. Astudy should be made on the effect of higher levels of phosphate on algal growth. A study should be made on the effect of detergents on fish or other 2.
A study should be made on the synergistic effect of nitrates and aquatic life, Q2. Why did you give it that rating?
What rating will you give that output? Why did you give it that score? You might have asked: Do scientists almost always follow the steps in the experimental method in the order they were described in the previous lessons? In reality, the answer is NO. They may not always follow all the steps in the experimental method as they have been described. The steps may not even be followed in the same order.
While performing an experiment, a scientist may observe something totally unexpected, something that might require a change in his or her hypothesis. In this situation, the problem came after a hypothesis. Or a scientist might not even start out with particular problem because, as he or she observes unexpected results, he or she might look at the situation in a new way or consider a new problem.
In this case, the problem followed an experiment. Still, another reason why scientists deviate from some rules when conducting science investigations is when it is not possible to control one variable at a time. For example: When studying why the path of a typhoon changed, it is difficult to isolate the atmospheric temperature and pressure from the moisture content of air. The factors that affect typhoons have to be studied all together and according to how these factors teract with each other.
Similarly, a landslide occurs because of the interactions of the following: amount and duration of rainfall, topography of the place, and kind of soil cover. The basic steps in conducting science investigations are: identifying the problem; gathering information about the problem; formulating a hypothesis; testing the hypothesis; seeking out patterns and regularities: drawing a conclusion; verifying the conclusion; and making generalized statements or predictions.
The list below gives topics or problems you might want to investigate for your nce class, 1. Your father is an ice cream vendor.
Which local materials will keep the ice from melting fast? Soil in your garden is sandy. How can its water-holding capacity be improved?
How can you prevent the growth of molds on bread? Will plants grow in any other media aside from soil? Which color absorbs more heat—black or red? What do you notice about the above-mentioned sample problems listed and the ones students submit for science fairs? Yes, they are real - life problems! Remember: Science is not just about doing laboratory work. Science is helping us make sense of the materials, events, and phenomena around us through the use of our senses.
Some scientists use their intuition; others use trial and error. Stil, others discover something by chance. Most use the experimental method in finding truths about nature and cause-effect relationships.
The experimental method requires an investigator to ask a question and to give it a tentative answer hypothesis. Scientists then design and set up an experiment to test the hypothesis.
They gather pertinent data for certain period of time. They organize and analyze the data gathered to answer the question or problem being investigated.
This method enables anyone to arrive at a conclusion that is free from personal bias. Moreover, it allows one to look at everyday situations with an analytical mind. Investigating is just one activity in science, but a very important one. It requires the use of all the basic process skills you learned in Unit 1. These are important skills that will enable you to appreciate the content and activities in the succeeding units.
You find snake eggs undemeath untouched stone or wood. Give at least two hypotheses for this observation. Mina carried out an experiment using setups A, B, and C. In container Ashe had water with ice and a thermometer. In container B, she had tap water and a thermometer. In container C, she had warm water and a thermometer. In each of the three containers, she added sugar cubes. What do you think is Mina trying to find out? Rica could not unscrew the metal cap of a bottle of syrup.
She hypothesized that syrup must have caramelized inside the grooves of the metal cap. Her brother suggested to pour hot water over the bottle cover.
Her sister said to light a candle and heat the bottle cap over it. Do you think the methods suggested will help Rica open the bottle? Until now, the plant has not bloomed. What factors should you take into account in finding out how to make the orchid bloom? What will your experimental plan be? Jose wanted to find out how long it takes for parachutes made of different materials to fall on the ground.
He made parachutes of the same sizes and dropped them from different heights. Ifitis not a fair test, how can you make it fair? You have been assigned to provide music for the class party. The program is about to begin in a few minutes. But the karaoke you brought does not work. How will you apply the experimental method to determine the cause of the problem? You will find rocks and minerals from its solid part called the lithosphere.
You will find water in seas, oceans, lakes, and rivers. Water covers about three-fourths of the lithosphere which is called the hydrosphere. You will find gases in air which make up the atmosphere. There are many more. Try to think of other materials in your immediate environment.
With thousands of materials around you, how can you distinguish one material from another? You can investigate the properties of the materials you are interested in. Look for patterns and trends in your observations and then use these to devise some methods of classification.
Any method can be a great help in organizing, analyzing, and interpreting various data or information. A very common method of classification is based on physical properties, like state, shape, color, and texture. Another classification can be based on chemical behavior how one material interacts with another material.
A third method could be based on uses. You can devise your own. The trees, rocks and soil, and the insects in your garden are all matter. Likewise, the water you drink, the gasoline and motor oil in the vehicle you ride in, and the air that you breathe are all matter. Even the bacteria and viruses that you cannot see with your unaided eyes are considered matter.
One way that scien- tists use to classify matter is to group them into living and nonliving. Generally, we classify matter as living if it breathes, moves, eats, grows, responds to things and situations around it, and has the ability to reproduce its own kind. Without these characteristics a piece of matter is considered nonliving.
However, some characteristics of living things are used to describe nonliving things. In what way then are living things different from nonliving things?
For instance, you need food in order to survive. Some of these simpler substances are then converted into nutrients for use in the repair of your worn-out tissues. Some are converted to energy essential for your everyday activities such as breathing, digesting, absorbing, converting food into body parts, or eliminating what is not needed or is poisonous to the body.
This series of processes is called metabolism. Only living things metabolize. The result of these metabolic processes is that the living thing actually grows.
Growth results in the conversion of substances from the environment, like air, water, and food, into a part of the organism's body. Such a growth can only come from within. Most plants grow almost unceasingly throughout their lives. But animals, including man, have a definite growth period, which stops when they reach adulthood, At this point they would have reached a maximum height.
Another characteristic that differentiates living things from nonliving things is their ability to reproduce their own kind. Plants can reproduce themselves by a variety of methods. New plants can grow from spores, seeds, stem cutlings, suckers, runners, and other human-devised techniques, such as grafting, budding, and marcotting. Animals likewise reproduce their own kind. Frogs reproduce frogs and cats reproduce cats. You have the characteristics of either your mother or your father or both because you came from both of them.
Sugar is sweet and often used in the form of small crystals. When you add some white sugar to water, the water remains colorless but becomes sweet. The resulting water is no longer the original tasteless water but has become a combination of two materials, sugar and water.
Where did the sugar go? Why can't you see it anymore? It is still there but its particles are no longer visible to the unaided eye. Water and sugar are called substances.
Together they form a kind of matter called mixture. The components of a mixture are called solute and solvent. In the sugar-water mixture, sugar is the solute and water is the solvent. Normally, the component with the greater amount is considered the solvent.
The solute has lesser amount and is the one that dissolves in the solvent. The composition of mixtures varies because the amounts of its components also vary. A mixture may be homogeneous and heterogeneous. Homogeneous mixtures are uniform throughout. The composition is the same in all directions in the mixture. The solute and solvent particles that you observe in one direction are the same as those you observe in all others. The mixture of sugar in water is homogeneous. Heterogeneous mixtures are not uniform.
The composition is not the same in all directions in the mixture. Try to expand the definition of mixtures by observing other mixtures in Activity 3. Label the bottles A to E. Stir the water. Add a teaspoon of rubbing alcohol to Bottle B. Add a teaspoon of sand to Bottle D. Do not put anything to Bottle E, a. What does Bottle E represent? Let the bottles stand undisturbed for about 10 minutes and observe again 7. Focus a lighted peniight on the mixture in each bottle. Look at the mixture at right angle to the path of light, b.
What was formed in each bottle? Did you get the same results? Identify the solute and the solvent in each mixture. What did you observe after a ray of light was focused on the mixtures? Unlike sugar, sand does not disappear in water. It is not evenly distributed within the solvent. Much of it readily settled at the bottom of the container. Some were suspended in water but later settled at the bottom just like the rest of the particles.
The mixture of soil in water is heterogeneous. Mixtures may be classified into solutions, colloids, and suspensions according to their particle size.
Solutions and colloids are homogeneous mixtures while suspensions or coarse dispersions are heterogeneous mixtures. The particles of solutions and colloids are smaller than those of suspensions, Solutions have the smallest particles. The particles of water and alcohol are spread uniformly throughout the solution. Liquid solutions are transparent. You can see through them. The mixture remains stable and does not separate after standing for any period of time.
The particles are so small that they cannot be seen by the unaided eye. Solutions can pass through a filter paper because their particles are smaller than the pores of the filter paper. The particles cannot scatter light focused on them. Some solutions may be colored but they will stil be transparent. Colloids are mixtures with particle size that are larger than those of solutions but smaller than those of suspensions.
The particles cannot be seen by the unaided eye but may be seen through a high-powered microscope. The particles of colloids are small enough to pass through a filter paper but large enough to prevent light from passing through and so scatters light. Fog and milk are examples of colloids. Colloids look homogeneous to the naked eye but often appear murky or opaque.
Suspensions are mixtures with particle sizes that are greater than solutions and colloids. That is the reason why they are visible to the naked eye while solutions and colloids are not. The particles cannot pass through a filter paper.
Suspensions are also murky and opaque and they do not transmit light. Separating the Components of Mixtures Can components of mixtures be separated from one another? Are components chemically combined? Activity 3. Name some properties of each, Prepare a Data Table for your observations. Puta tablespoon each of sand and rice grains in a clean bottle and stir.
Again observe the properties of sand and rice grains. Note down any changes that you see. Describe some methods for separating sand from rice grains. Try the method that your group thinks is the most efficient, that is, will separate most of the sand from rice grains at the shortest time.
Describe your results. Were the properties of sand and rice grains changed when they were stirred together? If yes, how have they changed? Can you still recognize the sand particles? How about the rice grains? What was produced when sand and rice grains were mixed? What method did you use to separate sand from rice grains? Which method is the most efficient? Station 2 Examine samples of water, sand, and table salt.
Name some properties of each. Enter your data in your prepared table. Half-fill a small beaker with water.
Add, in small portions, half a spoon of table salt, stirring the water after each addition. Compare the appearance of salt before and after adding it to water. Apply heat to the beaker and observe what happens with heating, Continue heating until half of the liquid is left in the beaker.
Repeat step 2 using sand instead of table salt. Compare the appearance of sand before and after adding it to water. Did the properties of table salt and water change when they were stirred together? If so, how did they change? Can you still recognize the salt crystals? How about the original water? What was produced when salt was mixed with water? What is left in the beaker? What was removed by heating?
What process occurred with continuous heating? Did you observe the same change when sand was mixed with water? Station 3 Examine samples of iron filings and ground charcoal. Enter your data in your prepared table, Mix equal amounts of iron filings and charcoal. Stir well. Compare their appearance before and after mixing. Did the properties of iron filings and charcoal change when they were stirred together? If so, in what way have they changed? Can you still recognize the iron filings?
How about charcoal?
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