LESSON PLAN

One-Step Equations with an Unknown Number

Apothem Team

Grade 3 · Algebra & Patterning

LESSON AT A GLANCE

Warm-up

5 min

Explore

15 min

Consolidate

10 min

Practice

12 min

Exit ticket

3 min

Warm-up

Show a balance scale with 5 cubes on each side: balanced. Add 3 cubes to the left: unbalanced. What must we add to the right to rebalance? (3 cubes.) This is the equation: 5 + 3 = 5 + n. n = 3. Every equation is a balance problem.

Explore

Equation sorting: each pair receives 12 equation cards (4 of each type: start, change, result unknown). Sort by type. Solve each. Verify each. Record in a table: equation, type, solution, check.

Consolidate

Practice

Students solve 9 equations (3 of each type), verify each, and write one word problem for each type. Exit ticket: solve and verify n + 24 = 61.

Exit ticket

Students solve 9 equations (3 of each type), verify each, and write one word problem for each type. Exit ticket: solve and verify n + 24 = 61.

TIP Verification is not optional. Make it a class norm: every solution must be checked. Ask: how do you know your answer is correct? Because I substituted it back and the equation is true.

WORKED EXAMPLES

Solve and verify: 27 + n = 45.

n = 45 - 27 = 18. Verify: 27 + 18 = 45. True. Solution: n = 18.

Is the sum of an even and an odd number always odd?

Even: 2n. Odd: 2m+1. Sum: 2n + 2m + 1 = 2(n+m) + 1. This is odd (an even number plus 1). Yes, even + odd is always odd. Concrete check: 6+3=9 (odd), 8+5=13 (odd), 10+7=17 (odd).

MATERIALS

•Balance scale for equation visualization

•Equation cards (all three structures)

•Verification recording sheets

•Even/odd investigation charts

•Number lines 0-100

WATCH FOR

!Students may solve result-unknown equations trivially (6+13=?) without realizing this is the same type as the others. Emphasize that all three are equations with the same structure.

!Students may skip verification when the answer comes easily. Require it always: the habit matters more than the specific check.