How to Evaluate Algebraic Expressions Using Algebra Tiles

Mashup Math

This educational video provides a clear, visual methodology for evaluating algebraic expressions using algebra tiles, a common mathematical manipulative. The video begins by defining the components of an algebraic expression—variables, operators, and numbers—before introducing a color-coded visual system where green rectangles represent variables (x), blue squares represent positive integers (+1), and red squares represent negative integers (-1). It establishes the crucial concept of "zero pairs," showing how positive and negative units cancel each other out, which is essential for understanding integer arithmetic. The core instruction demonstrates the process of substitution through two detailed examples. First, the narrator models evaluating 2x + 3 when x = 3, visually replacing variable tiles with the corresponding integer tiles to find the sum. Second, the video tackles a more complex problem involving negative numbers: evaluating 3x + 4 when x = -2. This example reinforces the zero pair concept as students watch red (negative) and blue (positive) tiles cancel out to reveal the final answer. Teachers can use this video to bridge the gap between concrete manipulatives and abstract algebraic notation. It is particularly valuable for introducing students to the concept of substitution and for reviewing integer rules in a tangible way. The video's step-by-step approach makes it an excellent tool for scaffolding lessons on evaluating expressions, helping visual learners grasp the underlying logic of algebraic operations before moving to purely symbolic calculation.