#2: THE FLOATING PAPER CLIP

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1 Activity #1: PILE IT ON. Materials: 1 DRY penny, 1 eye dropper, water. Procedure: Make sure the penny is dry. Begin by estimating the number of drops of water that can be piled on the penny before it spills over. Gently place drops of water on the penny until the water spills over. Record the results. Wipe up the water with a paper towel before leaving the station. Activity #2: THE FLOATING PAPER CLIP Materials: paper clip, container with water Procedure: Using a steady hand, see if you can get the paper clip to rest on the surface of the water in such a way that it will not sink. After you succeed, remove the paper clip and clean up any spilled water with a paper towel. Activity #3: WATER AS A SOLVENT Because of its high polarity, water is called the universal solvent. A solvent is a substance that dissolves, or breaks apart, another substance (known as a solute). A general rule that determines whether a substance will dissolve in a solvent depends upon its polarity. Polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes. In this activity, you will compare the ability of water, alcohol, and vegetable oil to dissolve certain solids. CAUTION: Rubbing alcohol is flammable, an eye irritant, and has fumes. Materials: graduated cylinder, 40 ml of alcohol, 3 beakers, 9 test tubes, test-tube rack, 40 ml of water, 40 ml of vegetable oil, sugar, salt, and margarine. Procedure: 1. Number your test tubes (TT) Pour 10 ml of water into TT marked 1-3. Be sure to use the graduated correctly labeled graduated cylinder to measure the water. 3. Pour 10 ml of alcohol into TT marked 4-6. Be sure to use the graduated correctly labeled graduated cylinder to measure the alcohol. 4. Pour 10 ml of vegetable oil into TT marked 7-9. Be sure to use the graduated correctly labeled graduated cylinder to measure the vegetable oil 5. Place a pea-sized amount of sugar in TT 1, 4, & 7 using the correctly labeled spoon. 6. Place a pea-sized amount of salt in 2, 5, & 8 using the correctly labeled spoon. 7. Place a pea-sized amount of margarine in TT 3, 6, & 9 using the correctly labeled spoon. 8. Cover each TT with your thumb and shake. 9. Observe and record the results. 10. Dump the contents of all the TTs into the waste container. 11. Wash the TT with soap & water and reorganize the station so that it is ready for the next class. Activity #4: THE MAGNETS What is polarity? Move the magnets around each other. Notice the orientation they are in when they are attracted to each other. Notice what happens when you put two magnets with the same ends together. How is this an example of the water molecule?

2 Activity #5: COMPARING WATER TO ALCOHOL Materials: beaker of water, beaker of alcohol, medicine dropper. Procedure: 1. Place one drop of water onto the back of your partner s right hand. 2. Place one drop of alcohol onto the back of your partner s left hand. 3. Observe for one minute and answer questions. Activity #6: CHEMISTRY OF LIVING THINGS Look at the elements and compounds that make up living things. Approximately 96 % of your body mass is composed of the elements oxygen, hydrogen, carbon, and nitrogen. The remaining 4% includes phosphorous, sulfur, sodium chloride, magnesium, potassium, iron, and iodine. Consider your body mass. How many pounds of each element/compound would you expect to find in your body? The percentages of each component are found on your data sheet. If you don t know your body weight, just estimate. You don t have to share your body weight with any classmates. You may use pounds or kilograms. Activity #7: LIFE UNDER A MICROSCOPE Materials: 1 drop pond water, eyedropper, microscope slide, cover slip, microscope 1. Make a wet mount slide. Place a drop of pond water in the center of a microscope slide and carefully put a cover slip over the water. 2. View the pond water sample under low power on the microscope. Use the coarse focus knob to bring the sample into focus. Draw and label any organisms that you see in the sample. 3. View the slide under high power. Use the fine focus knob to bring portions of the sample into focus. Draw and label any organisms, including details of their structures that you see in the sample. Activity #8: TYPES OF MICROSCOPES This station is a read-only station. You will not be conducting any investigations or collecting any data. Read the handout titled Microscopes and complete the table on your data sheet. Activity #9: ACCURACY AND PRECISION This station is a read-only station. You will not be conducting any investigations or collecting any data. Read the handout titled Accuracy and Precision and complete the questions on your data sheet.

3 Microscopes Adapted from Texas Biology, by Stephen Nowicki, copyright 2015, pgs Microscopes provide an enlarged image of an object. Some of the most basic concepts of biology such as the fact that cells make up all organisms were not even imaginable before microscopes. The first microscopes magnified objects but not produce clear images. By the 1800s, most microscopes had combinations of lenses that provided clearer images. Today s light microscopes are still based on the same principles. They are used to see living or preserved specimens, and they provide clear images of cells as small as bacteria. Light microscopes clearly magnify specimens up to about 1500 times their actual size, and samples are often stained with chemicals to make details stand out. Electron microscopes, first developed in the 1930s, use beams of electrons instead of light to magnify objects. These microscopes can be used to see cells, but they produce much higher magnifications so they can also show much smaller things. Electron microscopes can clearly magnify specimens as much as 1,000,000 times their actual size. They can even be used to directly study individual protein molecules. However, electrons microscopes, unlike light microscopes, cannot be used to study living organisms because the specimens studied have to be in a vacuum. There are two types of electron microscope. A scanning electron microscope (SEM) scans the surface of a specimen with a beam of electrons. Usually, the specimen s surface is coated with a very thin layer of a metal that deflects the electrons. A computer forms a three-dimensional image from measurements of the deflected electrons. A transmission electron microscope (TEM) transmits electrons through a thin slice of a specimen. The TEM makes a two-dimensional image similar to that of a light microscope, but a TEM has a much higher magnification. SEM and TEM images are artificially colorized with computers so that tiny details, such as leaf pores, or stoma, are easier to see.

4 Light Microscope

5 Accuracy and Precision Adapted from Texas Biology, by Stephen Nowicki, copyright 2015, pgs Quantitative data are gathered through measurement, the determination of the dimensions of something using a standard unit. The modern metric system, called the International System of Units, or SI, is the language for all scientific measurement. The quality of measurements can be described by their accuracy and precision. Accuracy is a description of how close a measurement is to the true value of the quantity measured. Precision is the exactness of a measurement. Accuracy and precision are demonstrated by the results of horseshoes tosses. When the horseshoes are close to each other, even if they are not near the goal post, the results are precise. When the horseshoes are centered around the goal post, even if they are not near each other, the results are accurate. When the horseshoes are centered around the goal post and close to each other, the results are both precise and accurate.

6 Name Per Lab: Properties of Water, Microscopes, and Accuracy & Precision Activity #1: Pile it On ESTIMATE: ACTUAL AMOUNT: 1. What property of water allows the water droplets 2. Describe why water forms droplets on a surface. to pile up on the penny? Activity #2: The Floating Paper Clip 3. What does it mean to float? (Hint: consider density) Is the paperclip actually floating? Explain. 4. What property of water allows a paper clip to rest on its surface? Activity #3: The Super Solvent Substance Water Alcohol Vegetable Oil Key Sugar +++ dissolves ~100% Salt Margarine 5. Which solvent dissolved the best? 6. What gives water the ability to dissolve things? ++ or + partial dissolve 0 did not dissolve 8. From this experiment would you conclude that a. sugar is polar or nonpolar? Explain. 7. What general rule determines whether a solute will dissolve in a solvent? Activity #4: The Magnets 9. What is polarity? b. salt is polar or nonpolar? Explain. c. margarine is polar or nonpolar? Explain. 11. Draw a water molecule with charges. 10. How are the magnets like a water molecule? Activity #5: Comparing Water and Alcohol 12. Which liquid evaporated first? 14. What property of water is this an illustration of? 13. When water evaporates, what type of bond (interaction) must be broken? Activity #6: Compounds in Living Things: Your Total body weight: 15. C= H2O= Ca= S= NaCl= Mg= P= N= 16. What are the four most common elements in your body?

7 Activity #7: Life Under a Microscope 16. Low Power High Power Activity #8: Types of Microscopes Type of Microscope Brief overview of how microscope works 17. Light Microscope Image (2D or 3D) Can be used on living organisms? Scanning Electron Microscope (SEM) 18. Transmission Electron Microscope (TEM) 19. Activity #9: Accuracy and Precision 20. Each of five students used the same ruler to measure the length of the same pencil. These data resulted: cm, cm, cm, cm, cm. The actual length of the pencil was cm. Describe whether accuracy and precision are each good or poor for these measurements. 21. Using two different instruments, a student measured the length of his foot to be 27 centimeters and centimeters. Explain the difference between these two measurements.

8 Compound Formula Percentage In Body Water H2O Males: 60% Females: Salt NaCl 0.2% 1. Convert each percentage to a decimal by DIVIDING by % % MULTIPLY each decimal by your body weight (in POUNDS or KILOGRAMS) 0.25 x (Body Weight) x (Body Weight)