Section 2-7/2-8 "Multiplying and Dividing Integers"

Technology objective: The students will use the calculator to see patterns and come up with the "rules" for multiplying and dividing integers.

Lesson:

Put the following multiplication problems on the board:

2 * 5 =

-2 * -5 =

-2 * 5 =

2 * -5 =

The next set of multiplication problems is:

10 * 3 =

-10 * -3

-10 * 3

10 * -3

Have them look for patterns and record any patterns they see in their journals. Also have them test their conjecture by trying several problems they make up on their own.

Put the following problems on the board:

8 / 1 =

-8 / -1 =

-8 / 1 =

8 / -1 =

Also, have them try the following:

18 / 3 =

-18 / -3

-18 / 3

18 / -3

Have them look for patterns and record any patterns they see in their journals. Also have them test their conjecture by trying several problems they make up on their own.

Reinforcement:

Based on this have the students come up with their own rules for multiplying and dividing integers to put in their journals.

Assignment:

Students will try these problems and predict the answers.

(+)(+)(+)

(+)(-)(-)

(-)(-)(-)

(+)(-)(+)(-)

(-)(-)(-)(-)

(-)(+)(-)(+)(-)

Explain any new patterns that you see. Make up some problems on your own and solve the problems without using a calculator.