A Metric Scavenger Hunt s1

A Metric Scavenger Hunt Pre-Lab Discussion In many science investigations, precise measurements must be made before conclusions can be formed. For everyday measuring we still use English units such as the inch, quart, and pound. But for scientific work, the metric system, or International System of Units (SI), is used. The universal language of science, the metric system allows scientists everywhere to share information.

In this investigation, you will have to "think metric" as you select objects that will correctly match the descriptions on your "metric scavenger hunt."

Problem How closely can you estimate the metric measurements of everyday items?

Materials (per group) Metric ruler 10-mL graduated cylinder 100-mL graduated cylinder Triple-beam balance Celsius thermometer

Safety Handle all glassware carefully. Note all safety alert symbols next to the steps in the Procedure and review the meanings of each symbol by referring to the symbol guide on page 10.

Procedure 1. Carefully read the description of each object you are to find in the "metric scavenger hunt."

METRIC SCAVENGER HUNT

a) An object that when filled to the top with water has a volume between _____ and_____ milliliters.

b) A metallic object that has a mass less than _____ grams.

c) A coin that has a diameter (the distance from one side of a circle through the center to the other side) between _____ and _____ millimeters.

d) An object with a length between _____ and _____ centimeters.

e) An item that when half filled with water has a volume between _____ and_____ liters.

f) An object with a normal temperature of 37°C. (Hint: You brought this object to class!)

g) An object that has a mass between _____ and _____ centigrams.

h) An object that has a volume between _____ and _____ cubic centimeters.

i) An object with a length between _____ and _____ decimeters. (You may not be able to take this object to your lab station.)

j) A substance with a temperature between _____ °C and _____ °C.

k) A person with a mass between _____ and _____ kilograms. Data Table 1

Description Possible Objects a b c d e f g h i i k

Data Table 2

Description Object Measurement Was Object Within Given Range? a b c d e f g h i i k

Analysis and Conclusions 1. Which objects were easiest to find? Hardest? Why?

2. Was it easy to "think metric"? Why?

3. Would students in other parts of the world have difficulty "thinking metric"? Why?

4. Why is it important that all scientific measurements be made using metric units

Critical Thinking and Application 1. The metric system is based on the number 10 and is a decimal system of measurement. What United States system is based on the number 10?

2. The United States is one of the few countries in the world that does not use the metric system for everyday measuring. Do you think Congress should pass a law requiring the use of the metric system throughout the country? Explain your answer.

3. If the United States did convert to the metric system, how would you implement this change?

Going Further 1. In the laboratory investigation, you have worked with SI units for measuring length, mass, temperature, and volume. Other SI base units include the second, ampere, kelvin, mole, and candela. Kind out what these SI base units are used to measure and report your findings to your classmates. 2. Conduct a survey to determine the familiarity of different age groups with the metric system. Questions might include the base units for different types of measurements and the prefixes used for making smaller and larger measurements.

Part 2: Observing the Uncertainty of Measurements Pre-Lab Discussion Biologists use a wide variety of laboratory tools to make scientific measurements. Some basic tools of measurement are the meterstick, triple-beam balance, graduated cylinder, and Celsius thermometer. The accuracy of a scientific measurement depends on three things: the smallest unit on the measuring scale, the ability of the observer to read the scale properly, and the degree of precision of the measuring instrument and scale. In this investigation, you will learn about the uncertainty of measurement and how accurately matter can be measured using common laboratory instruments.

Problem How accurately can matter be measured?

Materials (per station) Station 1: meterstick Station 2: meterstick Station 3: metric ruler regular object Station 4: 100-mL graduated cylinder 150-mL beaker of colored liquid Station 5: triple-beam balance or electronic balance small pebble Station 6: 100-mL graduated cylinder 150-mL beaker of water irregular object Station 7: Celsius thermometer and water 250-mL paper towel

Safety Put on a laboratory apron if one is available. Handle all glassware carefully. Note all safety alert symbols next to the steps in the Procedure and review the meanings of each symbol by referring to the symbol guide on page 10.

Procedure 1. Station 1: Use the meterstick to measure the length and width of your science classroom. If the room has an irregular shape, measure the longest width and the longest length. Express your measurements in meters and record them in the Data Table.

2. Station 2; Use the meterstick to measure the length and width of your desk or lab table. If the table lias an irregular shape, measure the longest width and the longest length. Express your measurements in centimeters and record them in the Data Table.

3. Station 3: Use the metric ruler to find the volume of the regular object. Volume is found by multiplying the length times the width times the height of the object. Express the volume in cubic centimeters and record it in the Data Table.

4. Station 4: Use the graduated cylinder to find (he volume of the colored liquid in the beaker. Remember to always read a graduated cylinder at the bottom curve of the meniscus. Pour the liquid back into the beaker. Express your measurement in milliliters and record it in the Data Table.

5. Station 5: Make certain (hat the riders on the triple-beam balance are moved all the way to the left and that the pointer rests on zero. Place the pebble on the pan on the triple-beam balance. Move the riders until the pointer is at zero. Express your measurement in grams and record it in the Data Table. Remove the pebble and return all riders to the far left of the balance.

6. Station 6: Fill the graduated cylinder half full with water from the beaker. Find the volume of the irregular object. Express the volume of the object in cubic centimeters and record it in the Data Table, Carefully remove the object from the graduated cylinder. Pour the water back into the beaker.

7. Station 7: Use the Celsius thermometer to find the temperature of the ice water. Express the temperature in degrees Celsius and record it in the Data Table. Remove the thermometer and carefully dry it with a paper towel.

8. Your teacher will construct a large class data table on the chalkboard. Have one member from your group record your data on the class data table. Observations Data Table

Station Measurement

1. What is the smallest unit shown on the meterstick?

2. What is the smallest unit shown on the metric ruler?

3. What is the smallest unit shown on the graduated cylinder?

4. What is the smallest unit on the triple-beam balance?

5. What is the smallest unit on the Celsius thermometer?

Analysis and Conclusions

1. Study the class data table. Do each group's measurements have the exact same value for each station?

2. Which stations had measurements that were most nearly alike? Explain why these measurements were so similar.

3. Which stations had measurements that were most varied? Explain why these measurements were so varied.

Critical Thinking and Application 1. Why is it important for the riders on a triple-beam balance to always start at the far left of the balance?

2. Of the following graduated cylinders—100 mL, 25 mL, or 10 mL—which would you use to most accurately measure 8 mL of a liquid? Explain your answer.

3. Which is more accurate for measuring liquid volume, a beaker or a graduated cylinder? Explain your answer.

4. Describe two variables that might affect the accuracy of your measurement of volume when using a metric ruler to measure the dimensions of an object.

Going Further 1. Calculate the average (mean) of the measurements at each station. To do this, add each measurement to find a total and then divide by the number of measurements. An average of several measurements is usually more precise than a single measurement. 2. Repeat the investigation, this time aiming for the best precision and accuracy possible. Record the measurements as you did before and calculate a class average for each station. Compare the measurements and averages for the two trials. Discuss factors that led to more precise measurements.