## Skin Weight

In this lesson, students complete a chart by multiplying or dividing a given value, compare two categories in a line graph, and identify number patterns.

Write the following chart on the chalkboard or overhead:

Start | Finish |

Ask students how they would get to start from finish. Most students will say that you can simply divide the start number by 12 to arrive at the finish number. Some students may say that you can also multiply the finish number by 12 to get the start number.

Write the following chart on the chalkboard or overhead:

Start | Finish |

Once again, ask students how they would get to start from finish. Most students will say that you can simply multiply the start number by 5 to arrive at the finish number. Some students may say that you can also divide the finish number by 5 to get the start number.

(Note: You may wish to include some numbers with decimals or fractions in your chart.)

Distribute the Skin Weight Activity Sheet to each student.

Discuss the rule of thumb on the Activity Sheet to the students. Give an example: "The weight of a 320-pound man's skin is determined by dividing 320 by 16." Thus, his skin weighs 20 pounds.

Give students time to individually complete the chart. As a class, make sure all students have completed the chart correctly before continuing.

Explain how to plot the graphs using a blue crayon for the body weight and a red crayon for the weight of the skin. Give students time to complete the graph using Graph Paper.

In pairs, discuss the completed graphs. Circulate through the classroom to verify the accuracy of the graphs.

- Two colored crayons for each student (preferably red and blue)
- A local newspaper or Internet news source
- Graph Paper
- Skin Weight Activity Sheet

**Assessment Option**

You may wish to collect the Skin Weight Activity Sheet as a means of assessment. Solutions to the chart are as follows:

- 160, 10
- 64, 4
- 100, 6.25
- 88, 5.5
- 128, 8
- 8, 0.5
- 48, 3
- 232, 14.5
- 36, 2.25
- 144, 9

**Extensions**

- In the sports section of the newspaper (or Internet news source), find the weights of ten different athletes. Figure the weights of their skins and then rank the weights from highest to lowest. What is the difference between the highest and the lowest?
- Move on to the next lesson,
*Whale Weight*.

### Whale Weight

represent the information in graphic chart form, and generalize the results of an investigation. Specifically, students explore the relationship between a whale's length and its weight.

### Learning Objectives

Students will:

- Complete a chart by multiplying or dividing a given value.
- Compare two categories of information in graphic form (line graph).
- Identify number patterns.

### NCTM Standards and Expectations

- Formulate questions, design studies, and collect data about a characteristic shared by two populations or different characteristics within one population.

- Select, create, and use appropriate graphical representations of data, including histograms, box plots, and scatterplots.

### Common Core State Standards – Practice

- CCSS.Math.Practice.MP8

Look for and express regularity in repeated reasoning.