Lesson 25.1 Using Algebra to Prove Conjectures 1

In this lesson, students experience the power of algebra as they prove number tricks using algebraic expressions. Earlier lessons in the cluster focused on variables, writing and simplifying expressions, and solving equations. In later lessons, students simplify more difficult expressions, solve more complex equations, and use algebra to solve a variety of problems.

Some important features of this lesson: In week 11, students used a small cup to represent an unknown, and a marker to represent a numerical value. This lesson uses the same manipulative model (see pictures on SP2). The process of building (concrete), drawing (semi-concrete), and recording symbols (abstract) are stressed, just as they were previously in week 11 (SP2-5). Conjectures were made based upon empirical evidence in previous lessons, but this lesson introduces the power of algebra as a means to prove a conjecture (see Math Background box on TP4).

Download Lesson 25.1 (PDF)