Although urine is sterile, it has hundreds of different kinds of wastes from the body. All sorts of things affect what is in your urine, including last night’s dinner, how much water you drink, what you do for exercise, and how well your kidneys work in the first place. This experiment will show you how the kidneys work to keep your body in top shape.


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Materials


  • 1 liter of water per student
  • 1 can of soda per student
  • 1 sports drink, like Gatorade, per student
  • Red food dye
  • Chalk (or a handful of sand)
  • Coffee filter or cheesecloth
  • pH paper strips
  • Disposable cups
  • Clean glass jar
  • Rubber band
  • Measuring cups

If you are doing the optional Third Bonus Experiment:


  • solution your teacher has prepared for you
  • pipe cleaners
  • cleaned out jar or bottle (pickle, jam, or mayo jar)
  • water
  • borax

Download Student Worksheet & Exercises


Experiment

First Experiment: How Quickly Do the Kidneys Process Fluids?


  1. Drink a liter of water quickly (in less than five minutes).
  2. Wait 20 minutes (you can start on the second part of this lab while you wait) and then collect your urine in a disposable cup in the bathroom and use a pH testing strip to test the pH by dipping it in the cup.
  3. Repeat four times so that you have four samples collected 20 minutes apart.
  4. Repeat steps 1-3  for two different liquids, such as a sports drink and a soda.
  5. Complete the data table for all three liquids.

Second Experiment: Kidney Filtration


  1. Crush a piece of chalk and place it in a clean glass jar. (You can alternatively use a handful of sand from the playground if you don’t have chalk.)
  2. Fill the jar partway with water.
  3. Add a few drops of red food coloring to the water.
  4. The chalk (or sand) represents toxins in the blood. The water represents the blood.
  5. Place a coffee filter (or cheesecloth) on top of the jar and secure with a rubber band. This coffee filter is your kidney.
  6. Tip the jar over a disposable cup and pour the contents into the disposable cup. This is the kidney filtering the blood.
  7. Observe what the filter traps and what it doesn’t and record your observations in the data table.

BONUS Third Experiment: Kidney Stones


  1. A kidney stone is something that develops in the urinary tract from a crystal. Crystals start from “seed crystals” that grow when placed in the right solution.
  2. Use a pipe cleaner to create a shape for crystals to cling to (suggestion: cut into 3 lengths and wrap around one another). Curl the top pipe cleaner around a pencil, making sure the shape will hang nicely in the container without touching the sides.
  3. Add 2 cups of water and 2 cups of borax (sodium tetraborate) into a pot. Heat, stirring continuously for about 5-10 minutes. Do not boil, but only heat until steam rises from the pan.
  4. When the borax has dissolved, add more, and continue to do so until there are bits of borax settling on the bottom of the pan that cannot be stirred in (It may be necessary to stop heating and let the solution settle if it gets too cloudy). You’ll be adding in a lot of borax!  You have now made a supersaturated solution. Make sure your solution is saturated, or your crystals will not grow.
  5. Wait until your solution has cooled to about 130oF (hot to the touch, but not so hot that you yank your hand away). Pour this solution (just the liquid, not the solid bits) into the jar, and add the pipe cleaner shape. Make sure the pipe cleaner is submerged in the solution. Put the jar in a place where the crystals can grow undisturbed overnight, or even for a few days. Warmer locations (such as upstairs or on top shelves) are best.
  6. NOTE: These crystals are NOT edible! Please keep them away from small children and pets!

 


Kidneys Process Fluids Data Table

Record the pH and volume (did you urinate a lot, medium, or little?)


Drink Type


20 min


40 min


60 min


80 min


 


Urine tests look at different components of urine. Most urine tests are done to get information about the body’s health and clarify problems that it might be having.  There are over 100 different kinds of urine tests that can be done. Depending on the test, scientists look for different things.


The most obvious, and the one you can do yourself at home, is to look at the color of urine, which is normally clear. Many different things affect urine color, and the darker it is, the less water there is in it. Vitamin B supplements can turn it bright yellow. If you like to eat blackberries, beets or rhubarb, then your urine might be red-brown.


The next thing to check is smell. Since urine doesn’t smell much, it’s a signal if it suddenly takes on an unusual odor. For example, if you have an E. coli infection, your urine will take on a bad odor.


Scientists also check the specific gravity, which is a measure of the amount of substances in the urine. The higher the specific gravity number measures, the more substance is in the urine. For example, when you drink a lot of water, your kidneys add that water into the urine, which makes for a lower the specific gravity number. This test shows how well the kidneys balance the amount of water in urine. The specific gravity for normal urine is between 1.005-1.030.


pH is a measure of how basic or acidic something is, and for a urine test, it’s the pH of the urine itself.  A pH of 7 is neutral, a 9 is strongly basic, and a 4 is strongly acidic. Using a strip of pH paper will tell you how basic or acidic your urine is. Normally, pH is between 4.6-8.0 for urine.


Protein is not supposed to be in the urine, unless you’re sick with a fever, just had a hard workout session, or are pregnant. Scientists look for protein to be present in the urine to detect certain kinds of kidney diseases.


Glucose is sugar in the blood, and usually there’s no glucose in urine, or if there is, it’s only a tiny bit. When scientists detect glucose in the urine, it means that the body’s blood sugar levels are very high, and they know they need to look into things further.


When scientists find nitrites, they know that bacteria are present, especially the kind that cause a urinary tract infection because bacteria make an enzyme that changes nitrates to nitrites in the urine.


Strong, healthy people will have a couple of small crystals in their urine. If scientists find a large number of crystals, then they start looking for kidney stones. If they don’t find kidney stones, then they start looking at how the body metabolizes food to see if there’s a problem.


Most adults make about 1-2 quarts of urine each day, and kids make about 0.6-1.6 quarts per day


Kidneys Filtration Data Table

Amount of Chalk or Sand


Amount of Water


Color of Water after Mixed


Amount of Solids Filtered
Out by Cheesecloth


 


Questions:


  1. Which fluid produced more urine for the first experiment?
  2. Did the caffeine solutions cause the calcite stones to shrink or have no effect?
  3. What does pouring the chalky water through a coffee filter show?
  4. What are kidney stones and how are they formed?

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We have done some extensive experiments on taste buds: how they are categorized, what tastes they recognize, and we have even mapped their location on your tongue. But we haven’t yet mentioned this fact: not all people can taste the same flavors!


So today we will check to see if you have a dominant or recessive gene for a distinct genetic characteristic. We’ll do this by testing your reaction to the taste of a chemical called phenylthiocarbamide (or PTC, for short). The interesting thing about PTC is that some people can taste it – and generally have a very adverse reaction. However, some people can’t taste it at all.


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Here’s what you need


      • 1 vial of PTC paper
      • family members



Download Student Worksheet & Exercises


Here’s what you do


  1. Put the PTC paper in your mouth. If you have the dominant gene, it will usually taste pretty bitter. It might also be sour or even a little sweet. If it tastes like a piece of paper, you have a recessive gene.
  2. After testing your paper, be sure to note whether you are a taster or non-taster.
  3. Now test at least five more people in your family and note their reactions as tasters or non-tasters. Also note their relationship to you.
  4. If you have enough PTC paper, make a genetic tree of your responses. Put Mom and Dad at the center and list you and your siblings branching out beneath them. Then list both sets of grandparents above each of your parents. Circle the names of family members who test positive and leave the negative testers uncircled.

What’s going on?


The gene that determines whether or not you can taste PTC is a part of your DNA (deoxyribonucleic acid). It is the genetic blueprint that you were born with and it determines everything about you: from hair color to the size of your feet. But DNA also plays an important role in how your five senses function. Colorblindness is a genetic deficiency in which a person cannot see colors has a difficult time with distinguishing them. It can range in severity. Some people who are colorblind can’t tell the difference between colors like red and green, but some see no colors at all. Everything looks like a black and white movie to them. Just like colorblindness, our taste sensitivity can vary. Maybe this explains why some people like liver and brussel sprouts and others can’t stand them!


So to relate this to our test, the ability to taste PTC comes from a gene. We know that if both of your parents can taste it, there is a high likelihood that you will be able to taste it, too. About 70%, or 7 out of 10, people can taste it. But what does it mean?  In truth, not a lot. It doesn’t mean you have a highly developed palate or a better sense of taste. It just means you are lucky enough to have inherited a gene that allows you to taste a disgusting, bitter chemical on a piece of paper. Congratulations!


Exercises


  1. What are the tiny hair-like organelles that send taste messages to your brain called?
  2. What are the bumps on your tongue called?
  3. What kind of trait does this experiment test?

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Stethoscopes are instruments used to amplify sounds like your heartbeat. Your doctor is trained to use a stethoscope not only to count the beats, but he or she can also hear things like your blood entering and exiting the heart
and its valves opening and closing. Pretty cool!


Today you will make and test a homemade stethoscope. Even though it will be pretty simple, you should still be able to hear your heart beating and your heart pumping. You can also use it to listen to your lungs, just like your doctor does.


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Here’s what you need


  • 3 12-inch lengths of rubber hose
  • 1 “T” connector
  • 1 funnel



Download Student Worksheet & Exercises


Here’s what you do


  1. Take two pieces of hose and work them onto the top ends of the “T” connector. Put the remaining piece of hose onto the bottom of the “T.” The tool you have made should look like a simple stethoscope, but there are no super cold metal end pieces to worry about with yours.
  2. Put the funnel into the bottom hose – the one hanging from the bottom of the “T” connector. You know have a functioning stethoscope. One word of warning: NEVER YELL INTO THE FUNNEL WHILE THE STETHOSCOPE IS ATTACHED TO SOMEONE’S EARS. THIS COULD DAMAGE EAR DRUMS!
  3. Gently insert the side tubes into your ears. Put the funnel on your chest, just to the left of your breastbone. Listen for your heartbeat. If you are in a sufficiently quiet room you may even be able to hear the opening and closing of your heart’s valves.
  4. After you’ve found your hear, try moving the stethoscope to various areas of your chest and listen for different sounds made by your heart. Ask if you can listen to a friend or family member’s heart. Are the sounds made by another heart the same or different?
  5. Now listen to your lungs, placing the end of the stethoscope just above and to the left of the bottom of your ribcage (Point A), to the right of the bottom of your ribcage (Point B), and just below where your ribs start (point C). Also listen in the middle of your back to the left (point D) and right of your spine (point E). In each spot, take a deep breath and listen for the sound of air entering and exiting the lungs.
  6. For your data records, record how many times your heart beats in a minute while you are quiet and sitting.
  7. Next, do 100 jumping jacks. Sit down immediately and check your heart. Record the number of beats per minute for jumping jacks in your data.
  8. Finally, go outside and run for 3 minutes, non-stop. Then sit and immediately check your heart rate one more time. Record the beats per minute for running in your experiment data.

What’s going on?


Exercise creates a demand for oxygen in your muscles, which is received from work done by your heart and lungs. They get a message from your brain and start to work harder. You can see the proof of their hard work in your recorded data.


Exercises


  1. Approximately how big is your heart?
  2. Which body system is the heart a part of?
  3. What are some of this system’s jobs?
  4. How many chambers does your heart have and what are they called?
  5. How did the heart rate change when you exercised?

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Today you will make a calibrated, or marked, container that you will use to measure your lung capacity. You will fill the calibrated container with water, slide a hose into it, take a really deep breath, and blow in the hose. As the air in your lungs enters the container, it will push out the water inside. Just blow as long and as much as you can, then when you flip the bottle over you will be able to read the amount of water you have displaced. If you will subtract the water displaced from the total amount of water in the bottle, the result is your lung capacity.


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Here’s what you need


    • 1 2-liter soda bottle
    • 1 black marker, permanent
    • 1 12” length of rubber hose
    • 1 large plastic bowl
    • 1 cup measure


Download Student Worksheet & Exercises


Here’s what you do


  1. Fill the 1 cup measure with water. Pour this into the 2-liter bottle and mark the water level with a line using the black, permanent marker. Also, write 1 cup next to the line. Keep adding water, one cup at a time, marking each new 1 cup increment until you have filled the bottle with water.
  2. Now flip the newly-filled bottle of water over 1 cup measure until the cup is about 1/3 full. Put one end of the rubber hose in the top of the bottle (which should be now under water).
  3. Take a really deep breath – as deep as you can – and blow your breath out into the tube. Continue to blow until you can’t push any more air into the bottle. As air goes in the bottle, it pushes an amount of water equal to its volume out and into the bowl.
  4. Put the lid on the bottle and turn it over before lifting it out of the water. How much water is left in the bottle? Subtract this amount from 8.5 cups. This should be your lung capacity.
  5. Record your lung capacity in your data records as, “My lung capacity is ____________ cups.”  You can convert this number to milliliters by multiplying by 0.24. For example, 19 cups would equal 4.5 liters.

What’s going on?


A person who is 70 years old has breathed about 600,000,000 times in their life. But they have also breathed a lot of air – about 13,000,000 cubic feet. This is enough air to fill 52 blimps!


A man’s lungs have a greater capacity than a woman’s – it’s about 6 liters for a man and 4.2 liters for a woman. And since a grown-up has a greater lung capacity than a kid, it makes sense that a 10-year old might breathe 20 times per minute when a grown-up might breathe only 12 times in a minute.


Exercises


  1. Which body system are your lungs a part of?
  2. What are some other parts in this system?
  3. Explain this system’s major function.

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Food and air both enter your body through your mouth, diverging when they reach the esophagus and trachea. Food goes to the gastrointestinal tract through your esophagus and air travels to your lungs via the trachea, or windpipe.


You will be making a model of how your lungs work in this lab. It will include the trachea, lungs, and the diaphragm, which expands and contracts as it fills and empties your lungs.


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Here’s what you need


    1. 1 2-liter soda bottle, emptied and cleaned
    2. 1 pair of scissors
    3. 1”Y” valve hose connector
    4. 3 round, 9-inch balloons
    5. 1 #3 one-hole stopper
    6. 1 length of hose, 8-inch
    7. 2 rubber bands
    8. 1 jar of petroleum jelly


Here’s what you do


  1. Cut off the bottom of the 2-liter bottle. Ask an adult for help.
  2. Take the “Y” valve and secure the two balloons to the top branches with the rubber bands.
  3. Put a tiny bit of petroleum jelly on the end of the hose to make it easier to insert into the #3 stopper. Pull 6 inches of hose through the stopper and then thread the hose through the bottle’s neck. Insert the stopper into the top of the bottle.
  4. Put the end of the hose (that is now inside the bottle) into the base of the “Y” valve (which now has balloons on its other branches). Pull the hose through the stopper a bit. Also, pull the lungs up toward the top of the bottle.
  5. Tie a knot in the third, unused balloon. Cut it in half and stretch the part with the knot over the open bottom of the soda bottle. Make sure the bottom balloon is as tight as it can be.
  6. Grab the bottle with one hand, the knot at the bottom of the balloon with the other. Carefully pull the knot on the balloon down. What happens to the balloons in the bottle? Now let go of the knot and observe how this affects the balloons. Note your observations in the experiment’s data.
  7. Sketch your model and label its trachea, lungs, and diaphragm.

What’s going on?


By placing a stopper in the top of the bottle and putting the stretched rubber balloon on the bottom, you have created an enclosed system. The tube at the top of the bottle is the only way for air to enter or exit the model’s lungs. Pulling down on the balloon’s knot reduced the air pressure inside the lungs. As compensation, air was pushed down into the tube to equalize the pressure. This caused the balloon lungs to expand. When you released the knot, the air pressure forced the air out of the balloons.


If you need more help with identification, the tube acts as the trachea, the balloons are the lungs, and the balloon with the knot at the bottom is the diaphragm.


Did you know that an average person breathes about 24,000 times each day? If you live to be 70 years old, that means about 600,000,000 breaths. Make them count!


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Digestion starts in your mouth as soon as you start to chew. Your saliva is full of enzymes. They are a kind of chemical key that unlock chains of protein, fat, and starch molecules. Enzymes break these chains down into smaller molecules like sugars and amino acids.


In this experiment, we will examine how the enzymes in your mouth help to break down the starch in a cracker. You will test the cracker to confirm starch content, then put it in your mouth and chew it for a long time in order to really let the enzymes do their job. Finally you will test the cracker for starch content and see what has happened as a result of your chewing.


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Here’s what you need


    1. 1 package of soda crackers
    2. 1 5” pie tin
    3. 1 craft stick
    4. 1 0.5 oz bottle of iodine
    5. 1 pre-form tube
    6. 1 1 mL plastic pipette
    7. water



Download Student Worksheet & Exercises


Here’s what you do


  1. Take a cracker from the package and put it in the pie tin. Use your thumb to mash it up, making the pieces as small as possible. Add a small amount of water with the pipette. Mix everything up with the craft stick to make a mash of cracker.
  2. Now fill the pipette with iodine. When iodine comes in contact with starch, it changes in color from reddish-brown to a dark blueish-black. Take the pipette and squeeze a few drops onto the cracker mash in various spots. Record what you see in your experiment data.
  3. Take another cracker and chew it up for about 2 minutes. Do you notice any flavor changes as you are chewing? If so, note this. Be particularly aware of any sweet flavors.
  4. Spit the mash into the pre-form tube once you have chewed for 2 minutes. Use the pipette of iodine to add a few drops of iodine to the chewed mash. Note any change in color. If there is no starch, the iodine will stay reddish-brown in color. If starch is present, you will see the color change to a very dark blue-black as it did in step 2. Record what you see in your data.

What’s going on?


This lab gives you a good idea of what happens in digestion, which starts as soon as food enters your mouth. Actually, the process can start even before this as your body prepares for food. Have you ever had a wonderful smell make your mouth water? This is your body’s way of getting ready to get to work digesting that delicious food.


Once you take a bite and the enzymes start to do their job of breaking large, more complex molecules into smaller particles. In this experiment, starch got broken down into simple sugars that your body could easily move around and use as fuel.


There are three sets of saliva-secreting glands in your mouth. They include a gland in the back of your throat called the parotoid gland, one in your lower jaw called the submandibular gland, and the sublingual gland which is under your tongue. The three work together to secrete up to 2 liters of saliva each day.


Exercises


  1. What is the first step in the digestive process?
  2. How does saliva help to digest food?
  3. Name one or more of the main salivary glands and where they are located.

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When you exercise your body requires more oxygen in order to burn the fuel that has been stored in your muscles.  Since oxygen is moved through your body by red blood cells, exercise increases your heart rate so that the blood can be pumped through your body faster. This delivers the needed oxygen to your muscles faster. The harder you exercise, the more oxygen is needed, so your heart and blood pump even faster still.


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Here’s what you need


    • 1 clock with a second hand
    • 1 pencil



Download Student Worksheet & Exercises


Here’s what you do


  1. While sitting quietly, place your first two fingers of one hand onto the wrist of the other hand. Feel for the pulse of your radial artery. Practice taking your pulse in intervals of 6 seconds.
  2. After you have had some practice with the 6 second interval, take your pulse for this amount of time and multiply it by 10. The 6-second rate times 10 is your heart rate per minute. Record each for experiment data.
  3. Now stand up and do 50 jumping jacks. When done, sit down immediately and check your pulse. Again, record the 6-second pulse rate, multiply it by 10 and also record the pulse rate per minute.
  4. Finally, go outside and run around as fast as you can without stopping for 3 minutes. Again, immediately sit and take your pulse. Record the 6-second rate, multiply it by 10 and get your heart rate per minute.

What’s going on?


Exercising means your muscles need more oxygen. They ask your brain to tell your heart and lungs. When your heart gets the message, it starts to beat harder. Your lungs work harder, too. Together, your heart and lungs work as a team to provide the needed oxygen supply to your muscles. You can identify that this process is occurring by your heart rate increase and more rapid breathing rate.


Did you know that your heart is about the size of your fist? It is actually a muscle and it pumps more than a gallon of blood through your body each minute! An average heart rate is 70 beats per minute, but this can vary depending on age and fitness level. Based on 70 bpm, your heart will beat around 100,000 times per day. That’s more than 36 million beats a year!


Exercises


  1. Explain how to take a pulse.
  2. What units do we use to measure pulse?

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An oxygen and carbon dioxide exchange takes place in your bloodstream. When you breathe air into your lungs it brings in oxygen, which is carried from your lungs by red blood cells in your bloodstream. Cells of your body use the oxygen and carbon dioxide is produced as waste, which is carried by your blood back to your lungs. You exhale and release the C02. You will study this exchange in today’s lab.


You will be using a pH indicator known as bromothymol blue. When you exhale into a baggie, the carbon dioxide will react with water in the bag. This reaction produces carbonic acid, which starts to acidify the water. More breathes in the bag equal more carbon dioxide, which equal a lower (more acidic) pH. You will notice the bromothymol will turn green when the pH of the water is right about 6.8 and it will turn yellow when the pH drops further to 6.0 and lower.


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Here’s what you need


    • 1 1 oz. bottle of bromothymol blue
    • 1 straw
    • 1 resealable baggie
    • 1 bottle of ammonia
    • 1 pipette
    • water


Download Student Worksheet & Exercises


Here’s what you do


  1. Pour about 2 ounces of water into the baggie and add two capfuls of the bromothymol blue into it. Close the baggie well and swish the solution around inside it gently to mix. Note the color of the solution for your data record.
  2. Open the baggie a tiny bit and put the straw inside, but DO NOT drink the solution! It could make you sick. Close the bag tightly around the straw and gently blow into the solution. Again, be careful not to suck on the straw.
  3. Watch the color of the solution closely as you continue to blow into the solution and create bubbles of carbon dioxide gas. The color will change to a sea green color and then eventually it will change to bright yellow. Note each color change in your records.
  4. You can return the solution to blue by slowly adding a base – such as ammonia – to the solution in the bag. Bleach will also work. Please ask an adult to help with this. Add one drop at a time, shaking after each addition to mix the solution. You will be able to observe when the pH starts to change back by the color of the solution. It should turn back to green and then to blue.

What’s going on?


Bromothymol blue will change color in a pH range from 6.0 to 7.6.  It is an acid/base indicator. Its basic solution is at a pH of 7.6 or above – this is when it is blue. In acidic conditions, it will turn yellow – this is a pH of 6.0 or below. And when it’s in between the two, it will be the sea green color that you observed in your baggie.


Because carbon dioxide is a little acidic, when we breathe it out into the water and bromothymol blue solution its bubbles start to lower the pH. You saw a small change in pH with the sea green color, but as you continued to exhale and add carbon dioxide, the solution became more and more acidic. This eventually resulted in a pH at or below 6.0 and a bright yellow solution.


In order to exchange oxygen with carbon dioxide in your lungs, they have over 300,000,000 teeny little air sacs calls alveoli. In one minute, you breathe approximately 13 pints of air.


Exercises


  1. What is pH and how it is useful?
  2. What does a yellow color indicate with bromothymol blue?
  3. Is CO2 acidic or basic?

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Your body moves when muscles pull on the bones through ligaments and tendons. Ligaments attach the bones to other bones, and the tendons attach the bones to the muscles.


If you place your relaxed arm on a table, palm-side up, you can get the fingers to move by pushing on the tendons below your wrist. We’re going to make a real working model of your hand, complete with the tendons that move the fingers! Are you ready?


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Here’s what you need:


  • five flexible straws
  • scrap of cardboard (at least as big as your hand)
  • five rubber bands
  • 5 feet of string or thin rope (and a lighter with adult help if you’re using nylon rope)
  • hot glue with glue sticks
  • scissors
  • razor



Download Student Worksheet & Exercises


Exercises


  1. What types of muscles are connected to our bones?
  2. Which type of connective tissue connects our muscles to our bones?
  3. What do extensor tendons in our wrist do?
  4. What do flexor tendons do?

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Did you know that the patterns on the tips of your fingers are unique? It’s true! Just like no two snowflakes are alike, no two people have the same set of fingerprints. In this experiment, you will be using a chemical reaction to generate your own set of blood-red prints.


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Here’s what you need


  • 1 oz. bottle of baking soda or sodium carbonate (washing soda)
  • water
  • 1 sheet of goldenrod paper
  • 1 paper towel
  • 1 magnifying lens


Download Student Worksheet & Exercises


Here’s what you do


  1. Pour a couple teaspoons of the baking soda (sodium carbonate) into a cup of water. Swish your right index finger in the damp baking soda and then roll that finger on the goldenrod paper. This should leave a bright red fingerprint on the paper. Label it right index.
  2. Continue the procedure for each finger on both hands to make a full set of prints. Be sure to label each fingerprint as you make it to identify which print goes to each finger. Don’t forget to make prints of your thumbs!
  3. Compare your prints to the basic patterns in the guide. Check for features such as whorls or loops and label them appropriately on your prints. Use abbreviations such as A for accidental, PW for plain whorl, and DL for double loop.
  4. After you have identified the dominant pattern on each of your fingertips, prepare a simple chart for each hand to record the data by finger.
  5. When you are finished studying your own prints, ask a volunteer to let you make prints of their fingers.

What’s going on?


Goldenrod paper is made using phenolphthalein, a chemical that turns red when exposed to materials with relatively high pH. Baking soda (or sodium bicarbonate) is a base which has a pH of about 8.5. Rolling your baking soda covered fingers on the goldenrod paper creates a chemical reaction which produces a red fingerprint.


Exercises


  1. What are the three main types of patterns on fingerprints? Describe each.
  2. How do fingerprints have the potential to help solve crime?
  3. Why does baking soda (or washing soda) show up red on the paper?
  4. What kind of pH do bases have?
  5. What kind of reaction do we see when the red fingerprints show up on the paper?

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