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Examining Exercise

Investigation 4 – Lab

Back to Investigation 4

BE PREPARED

Supplies and Equipment:

Class Materials:

1 triple beam balance

Group Materials:

18 large (12 g) bears
18 medium (8 g) bears
24 small (4 g) bears
40 gram cubes
2 wood blocks
4 plastic buckets
4 brass fasteners
2 meter sticks
3 calculators
6 pieces of masking tape (5 cm in length)
1 marker
1 100 ml beaker filled with 55 g of split peas (Beaker A)
1 100 ml beaker filled with 81 g of split peas (Beaker B)
680 g of split peas

Individual materials:

1 Scientist Data Record

GET FOCUSED

Tell students that they will examine energy input and energy output in understand energy balance.

Teacher Preparation:

Use the triple beam balance to fill one (1) 100 ml beaker with 55 g of split peas for each group. Label each beaker “A.”
Use the triple beam balance to fill one (1) 100 ml beaker with 81 g of split peas for each group. Label each beaker “B.”
Organize the required materials at a distribution point.
Separate the class into five cooperative groups.

Instruction:

1. Direct each student pair to obtain the following necessary materials from the distribution point: eighteen (18) large (12 g) bears, eighteen (18) medium (8 g) bears, twenty-four (24) small (4 g) bears, forty (40) gram cubes, two (2) woodblocks, four (4) plastic buckets, four (4) brass fasteners, two (2) meter sticks, one (1) marker, one (1) 100 ml beaker filled with 55 g of split peas, one (1) 100 ml beaker filled with 81 g of split peas, and six (6) cm pieces of masking tape, 5 cm in length.

2. Explain that, in this Investigation, students will discover what happens to energy balance when different foods are consumed and different activities are carried out. Students will use a combination of models and calculations to investigate the association between energy input and energy output of two boys, Tim and Keith. The passages that follow are provided to assist your direction of the student through this part of the Investigation.

a. Tell students that they will use a beam and fulcrum or lever to represent energy balance. One side of the lever will represent each boy’s energy output, and one side will represent energy input.

b. Demonstrate the assembly of two (2) levers, one for each boy, using the following steps:

Assemble two (2) levers by placing one wood block at each end of the lab table. Center a meter stick on each block so that it balances freely. The wood block should be located at the midpoint (approximately 50 cm) of the meter stick.

The ends of each meter stick should extend past the edges of the lab table
Use masking tape to label the area below each lever. One lever should be labeled “Tim’s Balance” and the other lever “Keith’s Balance”.
Hang one empty bucket at the 0 cm end of each meter stick and attach it with a brass fastener (Figure 4.6). Secure the bucket handle by threading the brass fastener through the holes in the bucket handle and the meter stick and spreading the ends. These buckets represent Tim and Keith’s ENERGY OUTPUT. Label this bucket OUTPUT using masking tape.
Attach buckets to the 100-cm end of each meter stick using brass fasteners (Figure 4.7). These buckets represent Tim and Keith’s ENERGY INPUT. Label each of these buckets INPUT using the remaining two pieces of masking tape.

3. Write the following information on the board for the students, explaining that the same information can be found in Problem 1a of their Student Data Record. Tell students that these items will be used to represent Tim and Keith’s energy input and energy output. Direct students’ attention to the descriptions of the terms energy input and energy output in the table and check that students understand the concepts these terms denote.

INVESTIGATE

Trial 1:

Students will investigate the effects of food consumption, in the absence of energy expenditure, on energy balance. To begin, students will review and analyze two menus. One menu lists Keith’s energy input (food consumption). The other lists Tim’s energy input. Energy input is described as arbitrary units of energy.

Using the information on each menu, students will equate the foods described in each menu with units of energy and then use the split peas to represent energy input in their model. One gram of split peas is equivalent to 1 unit of energy input.

As students will focus on differences between the foods on each the menu, it may be necessary to draw students’ attention to the summary of energy input at the bottom of each menu as they prepare to determine the energy input of each boy. As students approach this part of the investigation they will be asked the following question:

What happens to energy balance if a person consumes food without expending energy?

Note: Caution students to pour the peas slowly to avoid having the apparatus fall, as the OUTPUT bucket is still empty at this point and will not remain stable if the peas are dumped rapidly into the bucket.

d. Beaker A holds 55 grams of split peas, which represents the 55 unites of energy that Tim ate during the day. Use this beaker to add the amount of energy that Tim ate to his INPUT bucket.

e. Beaker B holds 81 grams of split peas, which represents the 81 units of energy that Keith ate during the day. Use this beaker to add the amount of energy that Keith ate to his INPUT bucket.

f. Observe Tim’s model. What can you say about Tim’s energy balance at this point?

g. Observe Keith’s model. What can you say about Keith’s energy balance at this point?

Trial 2:

Students will review and analyze the energy expenditure or output for Keith and Tim from their waking hours until the end of a school day. The energy output for these activities is listed at the top of the activity table. Students will discuss the types of activities each boy performs with the members of their group.

In order to assist students in their understanding of the types of activities that require energy expenditure, it may be necessary to remind students that energy output includes not only the energy required to perform the various activities but also the energy the body uses for maintenance functions such as pumping blood, breathing, and maintaining cells (basal metabolic rate).

As students review the energy output for each boy, they will be asked to answer the following questions:

How would you describe the activities Tim and Keith performed during their school day?

Are they activities that use a lot of energy?

Trial 3:

Students will test the effects of performing the normal school day activities discussed in Trial 2 on Tim’s and Keith’s energy balance.

Students will place the appropriate amount of energy output in each boy’s output bucket using any combination of gram bears and gram cubes that equals the energy output for normal school day activities. After students adjust the energy levels of the balances, they will use their observations regarding the status of each energy balance to answer the following questions:

How would you describe Tim’s energy balance now?

How would you describe Keith’s energy balance now?

Trials 4-5:

Students will investigate the effects of differing activity levels on Tim’s and Keith’s energy balances through a process of calculation, prediction, and experimentation. Students are provided with two (2) sets of activities, each containing a mixture of low and moderate activities. Activity Set A also includes vigorous activities to provide students with an opportunity to observe how vigorous activity contributes to a healthy energy balance and provide a contrast to Activity Set B, which represents a more sedentary lifestyle.

In Trial 4, students will use calculations to determine energy expenditure for the different energy levels in each activity set. To assist students in the completion of this portion of the Investigation, it is recommended that the instructor refer students to the chart to the right chart on the board so that students may pool their results:

The instructor may wish to fill in the value for Vigorous activity under Set B to encourage students to choose options from their tables which require calculation so that the work load is distributed more equally between groups. Student groups will be directed to choose a calculation option. However, the instructor may opt to assign an option to each group to avoid duplication between groups.

In Trial 5, students will be asked to make and test the following predictions based on the results of Trial 4:

What will happen to Keith’s and Tim’s energy balance if they perform the activities in Set A?

What will happen to Keith’s and Tim’s energy balance if they perform the activities in Set B?

5. Upon completion of the experiment, provide an opportunity for students to quickly summarize what they have learned about energy input and output by directing them to answer Problem 7 on their Student Data Record.