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## Chapter 23

### Part 1: For the problem in the Teacher's Edition, page 604

Provide the students with a copy of the Problem Worksheet (PDF file).

Review multiplication of positive and negative numbers before students use the equation to fill in the table. Have the students demonstrate putting the value of t into the equation to get a value for h.

th
50(180)
55(135)
60(90)
65(45)
70(0)

### Part 2: Be an Investigator

A good time to do this investigation is after Lesson 5 on inequalities.

#### 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.

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

#### Doing the Investigation

Students should learn from this investigation that there is a big difference between less than 90°F and less than or equal to 90°F. Have the students share their evaluations of the experiments and discuss which temperatures fall within the range for the experiment and which do not.