Name______Class ______Date ______
Chapter 1 The Science of Biology
You may want to refer students to Measuring Length, Mass, Volume, Section 1Ð4 and Appendix C in the textbook for a discussion of and Temperature measurement. Time required: 40 minutes Introduction Doing experiments is an important part of science. Most experiments include making measurements. Many different quantities can be measured. Some examples are length, mass, volume, temperature, and time. Some quantities, such as length, can be measured directly. Others, such as speed, are calculated from other measurements. In science you will probably use metric units to estimate, measure, and record data. The three fundamental metric units are the meter for length, the gram for mass, and the liter for capacity. In this investigation you will carry out different types of measurements.
Problem What types of measurements are used to describe quantities?
Pre-Lab Discussion Read the entire investigation. Then, work with a partner to answer the following questions. 1. Which of the measurements in the investigation are familiar to you? Which will be new to you? Measuring mass and liquid volume may be less familiar to students than measuring length and temperature.
2. How will you record a distance that is 2 centimeters longer than 5 meters? 2 centimeters shorter? 5.02 m (or 5 m 2 cm); 4.98 m (or 4 m 98 cm). Remind students that 1 cm equals 0.01 m. If necessary, review converting between centimeters and meters.
3. How will you choose an object to measure in millimeters? Millimeters are very small, so the length to be measured should not be too large. An object like a paper clip would work well.
4. Why would you measure the contents of a paper cup in milliliters (mL) rather than in liters? The capacity is much less than a liter, so the measurement in liters will be a decimal less than 1. Measuring in milliliters gives a whole number answer rather than a decimal, and whole numbers such as 345 are easier to understand than decimals such as 0.345.
5. Estimating quantities is a useful and practical skill. Describe a plan you can use to improve your ability to estimate quantities. © Prentice-Hall, Inc. © Prentice-Hall, Repeatedly comparing estimates with actual measurements will improve a person’s ability to estimate. Encourage students to always estimate before measuring.
Biology Laboratory Manual B/Chapter 1 55 Materials (per group) meter stick millimeter ruler 250-mL graduated cylinder laboratory balance and metric masses thermometer 2 paper cups 30 cm of string table-tennis ball golf ball
Safety Wear your lab apron and safety goggles at all times during this lab. Be careful not to break any glassware. Note all safety alert symbols next to the steps in the Procedure and review the meaning of each symbol by referring to Safety Symbols on page 8.
Procedure 1. Find an object whose length can be easily measured in centimeters. Make a sketch of the object in the space below. Then measure and record its length.
length: ______
2. Picture in your mind a familiar distance nearby that you think is 5 m long. Write a description of this distance below (for example, “The distance from our classroom to room 203 down the hall”). Then measure the distance with a meter stick and record your result. How good was your estimate?
length: ______
3. Find an object whose width can be easily measured in millimeters. Make a sketch of the object in the space below. Then measure the object and record its length. © Prentice-Hall, Inc. © Prentice-Hall,
length: ______
56 Biology Laboratory Manual B/Chapter 1 Name______Class ______Date ______
4. Find a small object that fits easily on the pan of the balance scale. Make a sketch of the object in the space below, then find its mass in grams.
mass: ______
5. Fill a paper cup about two-thirds full with water. Pour the water into the graduated cylinder and record its volume in mL. CAUTION: Be careful not to break glassware. volume: ______6. The volume of a rectangular solid is measured in cubic centimeters (cm3). Find an object that is a rectangular solid. Then devise a way to find the volume of the object. What measurements will you need to make? Record each measurement and the volume of the object below. Volume equals length times width times height. Students should measure in tenths of centimeters.
volume: ______7. Fill a paper cup about two-thirds full with cool tap water. Place the thermometer in the water and find its temperature. Record your measurement below. Spill out the water. Now fill the cup with warm tap water. Use the thermometer to find the temperature of the water. Record your measurement. cool tap water: ______warm tap water: ______8. Use the balance to find the mass of the golf ball. Record your measurement below. Then find and record the mass of the table-tennis ball. mass of golf ball: ______mass of table-tennis ball: ______Now take a piece of string and use it to measure the circumference of the golf ball at its widest point. You can do this by wrapping the string exactly once around the golf ball, then measuring the length of the string. Record your measurement below. Repeat this procedure for the table-tennis ball. © Prentice-Hall, Inc. © Prentice-Hall, circumference of golf ball: ______circumference of table-tennis ball: ______
Biology Laboratory Manual B/Chapter 1 57 Analysis and Conclusions 1. Comparing and Contrasting Which of the measurements did you find easiest to make? Which did you find most difficult? Why do you think so? Millimeters may have been difficult because they are so small. Finding the circumferences may have been difficult because the string moves or stretches.
2. Comparing and Contrasting One student measured the height of a plant as 52 mm. Another student measured the same plant to the nearest tenth of a centimeter. What was the second student’s measurement? Was one method more precise? Explain your answer. The second student got 5.2 cm. The two methods are equally precise because 1 millimeter is the same as one-tenth of a centimeter.
3. Calculating A cube measuring 1 cm in each dimension holds 1 milliliter of water. Describe the dimensions of a cube that could hold 1 liter of water. What is the volume of this cube in cubic centimeters? The cube measures 10 cm on each edge. The volume is 10 cm x 10 cm x 10 cm, or 1,000 cubic centimeters, which equals 1 liter.
4. Measuring Why might two people measuring the same temperature get very different results? They may have used different units of measurement; for example, Fahrenheit and Celsius degrees.
5. Inferring Why might it be a good practice to measure a quantity several times and average the results? Minor errors in measurement would cancel each other. Also, an obviously incorrect measurement would stand out from the other data.
6. Comparing and Contrasting Look at the measurements that you recorded in step 8. In what way are these two balls similar? In what way are they quite different? They have about the same circumference, radius, diameter, and volume. The mass of the golf ball is
much greater.
7. Forming Operational Definitions Describe a single measurement that would describe the similarity and difference that exists between the golf ball and table-tennis ball. Some students may realize that density is the ratio that describes mass per unit volume.
Going Further Find a local map that shows distances to the nearest tenth of a mile. Then have a friend with a car drive a short distance, such as 3 miles. Your friend should try to drive at a constant speed; for example, 30 © Prentice-Hall, Inc. © Prentice-Hall, miles per hour. Time the trip with a stop watch or watch with a second hand. Calculate the speed (distance divided by time) and compare the calculated speed with the speed shown on the car’s speedometer. Do you think it is more accurate to calculate speed or to measure it? Give reasons for your opinion. 58 Biology Laboratory Manual B/Chapter 1