I created this PowerPoint lesson for my Algebra 1 classes. It corresponds to Section 2.4 in the Prentice Hall textbook -- California Algebra 1. This lesson shows students how to solve proportions by cross multiplying. Both algebraic problem and word problem examples are given. It also explains the difference between rates and ratios.
This addresses CA Standards:
4.0 Students simplify expressions before solving linear equations and inequalities in one variable, such as 3(2x-5) + 4(x-2) = 12.
5.0 Students solve multi-step problems, including word problems, involving linear equations and linear inequalities in one variable and provide justification for each step.
Common Core Standard:
A.EE.7 Solve linear equations in one variable.
a. Give examples of linear equations in one variable with one solution, infinitely many solutions, or no solutions. Show which of these possibilities is the case by successively transforming the given equation into simpler forms, until an equivalent equation of the form x = a, a = a, or a = b results (where a and b are different numbers).
b. Solve linear equations with rational number coefficients, including equations whose solutions require expanding expressions using the distributive property and collecting like terms.
Note: Math Type 3.0 and/or Math Type 5.0 were used to create this lesson.