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Using the TI-73: A Guide for Teachers

Patterns and Relations

8.Using the TI-73, lead students to alternative methods by reading the T-chart as a relationship between X and Y.

a.Tell students to look at the numbers in their T-chart and describe the rule that relates the number of lengths to the total number of beams. For example, As the number of lengths change, what happens to the number of beams? Have students share rules in small groups, and then with the whole class.

b.Write the rules on the board or chart paper so all can see. Students may suggest the following rules (or something similar):

∙The total number of beams is equal to 3 times the number of lengths plus 1.

∙The total number of beams is equal to 4 plus 3 times 1 less than the number of lengths in the bottom.

∙The total number of beams is equal to 2 times the number of lengths plus the number of lengths plus 1.

9.Ask students to describe their rules symbolically (mathematically) using L to represent the number of lengths and B the total number of beams.

Record the equations so the whole class can see them. They are related to the rules stated earlier.

∙The total number of beams is equal to 3 times the number of lengths plus 1.

B is 3 times L plus 1. B = 3L + 1

∙The total number of beams is equal to 4 plus 3 times 1 less than the number of lengths in the bottom.

B is 4 plus 3 times L minus 1. B = 4 + 3(L-1)

∙The total number of beams is equal to 2 times the number of lengths plus the number of lengths plus 1.

B is 2 times L plus L plus 1. B = 2L + L + 1

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