1. Proportional and Nonproportional Relationships

2. Vocabulary
Proportional: For a relationship to be constant there has to be a constant ratio. The graph of a proportional relationship will cross through the origin (0,0)
Nonproportional: No constant ratio. The graph will not cross the origin.

3. Is it Proportional?
Uptown pizzeria sells medium pizzas for $7 each but charges a $3 delivery fee per order. Is the cost of an order proportional to the number of pizzas ordered?
Find the cost for 1,2,3,and 4 pizzas and make a table to display numbers and cost.

4. At the beginning of the school year, Isabel had $120 in the bank
At the beginning of the school year, Isabel had $120 in the bank. Each week, she deposits another $20. Is her account balance proportional to the number of weeks since she started school?