Tip the Scales

Teaching Notes for Educators

Students solve linear equations on a balance scale that only stays level when both sides are equal.

• The math: to keep an equation true, do the same operation to both sides, using inverse operations to isolate the variable.
• Four tiers: one-step equations (grade 6), two-step equations (grade 7), variables on both sides, and equations with distribution (grade 8).
• Distributive property: the Expand and Factor toggle animates p(x + q) into px + pq, so the rule is visible.
• Several views at once: algebra tiles, the equation, and an expanded term list appear together, and Sandbox mode lets students test any value of x.
• Real life: variables on both sides model comparing two plans, such as finding when two phone or gym prices are equal, and one-variable equations cover unknown quantities in budgets and recipes.