Provides classroom activities for middle school math teachers to help students build a better understanding of addition and multiplication of integers, a skill necessary for success in algebra. Uses examples that incorporate both number lines and concrete models. Instructs how to add on a number line and add with manipulatives. Introduces and models multiplication of integers using a concrete model. Provides examples of problems with a positive leading factor and a negative leading factor. Uses concrete model of multiplication to explain why multiplying two negative numbers equals a positive product.