## Chapter 15

### Part 1: For the problem in the Teacher's Edition, page 374

Provide students with the Problem Worksheet (PDF file)

Students can practice their research skills by finding examples of graphs in newspapers. Have each student show a graph to the whole class and tell the class what it means. If you do see examples of any graphs that are done incorrectly, take the opportunity to talk about how you sometimes find graphs that misrepresent information.

If you do not want your students to find graphs in newspapers, you can bring in a few examples of graphs that you have found in newspapers. Try to find as many different kinds of graph as you can. After students have written their explanations of the graphs, discuss what each graph shows with the whole class.

Create a bulletin board of the graphs along with the explanations.

### Part 2: Be an Investigator

A good time to do this investigation is after Lesson 4 on reading and making line graphs.

#### Introducing the Investigation

Introduce the investigation by reading aloud the assignment at the top of the first page of the Description of Investigation and Student Report (PDF file), by having one of your students read aloud the assignment, or by having the students read the assignment individually.

To make sure the students understand how to read the graphs, ask questions such as:

**What was the high temperature on Day 4 in San Francisco?**(60°F)

Put students in groups of two to four to work on the investigation.

#### Doing the Investigation

Discuss the predictions the students made. Have them share their reasons for making each prediction. In the discussion, bring out the fact that once in a while there are very big changes in temperature, so there are other factors that weather people take into account besides looking at past temperatures.

#### Answers:

New York City: Answers will vary. Predictions between about 35°F and 50°F would make sense. Listen to students' arguments for their prediction. Some students might argue that it looks like the high temperature is going up, and predict a high temperature between about 45°F and 50°F.

San Francisco: Answers will vary. Predictions between about 55°F and 70°F would make sense. Listen to students' arguments for their prediction. Some students might argue that it looks like the high temperature is going down, and predict a high temperature between about 55°F and 60°F.

Honolulu: Answers will vary. Predictions between about 75°F and 85°F would make sense. Listen to students' arguments for their prediction.

#### Student Report

The assignment gives students an opportunity to make a prediction and state how they made the prediction, thus communicating about mathematics.