Topics · Patterns & Equations
Equations and mystery numbers
A letter can stand for a hidden number. An equation is a balance — keep both sides equal and the mystery number shows itself.
Finding an unknown is the start of all algebra.
More ways into this idea
- Play with itBalance LabLoad both pans, set the mystery weight, watch the tilt
- Play with itTwo-Step MachineMultiply then add — or swap them. Does order matter?
Step into a storyThe Locked GateThe code is unknown. The balance knows it anyway.- Make it a gameRule DetectiveFeed the machine numbers and catch its secret rule
- Make it a gameBalance RepairFix wrecked equations and free the mystery block
- Test yourselfA fresh mixed set, whenever you likeExplanations after every question. Nothing is recorded.
Common sticking points
- A common sticking point is reading = as 'the answer comes next' instead of 'both sides have the same value'. The balance picture fixes this.
- Another is changing one side of an equation only. On a scale you can SEE it: the sides stop matching. Whatever you do, do it to both sides.
Try this together
Put the same number of small objects (coins, blocks) on two sides of a table. Add 3 to both sides — still equal? Now take 2 from one side only. What happened? That's the whole secret of equations.
1–5 minutes, no materials to buy, nothing to hand in.
Ontario curriculum details
- C2.1Move between words, expressions and pictures
- C2.2Evaluate expressions with whole numbers
- C2.3Solve equations with whole numbers up to 100
- C2.4Solve and graph simple inequalities
Plain-language summaries. See the full curriculum for every expectation and the official source.