## Chapter 13

### Part 1: For the problem in the Teacher's Edition, page 318

Provide your students with a copy of the Activity page (PDF file).

Give the students graph paper and help them set up the graph, put the points on the graph, and draw a straight line through the points. Then ask them how they could use the graph to predict the temperature at 4,000 meters.

Answer:

The Celsius Temperature at an altitude of 4,000 meters would be -13°C.

### Part 2: Be an Investigator

A good time to do this investigation is after Lesson 1 on graphing points in the coordinate plane.

#### 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.

You might want to hold a geometry contest in your classroom. Give each team the three questions and reward the team(s) that does the best with a small prize.

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

#### Doing the Investigation

As you watch students doing this activity clear up confusions they might have about graphing points in the coordinate plane. For example, make sure they can distinguish between (2, 3) and (3, 2).

Answers:

**Question 1**

Draw the polygon with these vertices: (1, 2) (2, 4) (4, 4) (5, 2) (4, 1) (2, 1)

What kind of polygon is it? (hexagon)

**Question 2**

The figure is a rectangle. Name the missing coordinate.

(5, 1)

**Question 3**

The figure is a parallelogram. Name the missing coordinate.

(0, 3)

#### Student Report

The student report gives students an opportunity to show what they have done.

#### Extending the Investigation

Have students write their own questions of the type given here for the geometry contest. Have them give the answer to their question. Students can trade questions and try to answer each other's questions.