Mathematics Class 7
Finding the Unknown
An equals sign is a balance. Undo it, step by step, to find the number.
16 lessons · ~107 min total
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Lessons in this topic
- 0 Start here A roadmap: the equals sign as a balance, testing a number, and undoing steps to find a hidden number. · 4 min You are here
- 1 The equals sign is a balance An equation claims that its two sides name the same number. · 7 min
- 2 One waits, the other claims A line with no equals sign waits for a value. A line with one makes a claim you can test. · 6 min
- 3 Is this the one? Work out each side at a chosen number, and let the two answers decide. · 6 min
- 4 Take it off both sides Adding or taking away the same number on both sides keeps the answer. One side alone does not. · 7 min
- 5 Share both sides Multiplying and sharing undo each other — share both sides to free the letter. · 7 min
- 6 Two steps, undone backwards When two moves were made, the last one done is the first one undone. · 7 min
- 7 From a puzzle to a line Split the amount that repeats from the amount that happens once, and write one line. · 7 min
- 8 Put it back in The last step of a solve is putting the answer back into the equation you started with. · 7 min
- 9 The unknown on both sides Lift the smaller number of letters off both sides first. · 8 min
- 10 A bracket in the equation Share both sides, or multiply into the bracket. Same answer. · 8 min
- 11 When no number fits Cancel the k’s. If the leftover is false, no number fits. · 7 min
- 12 Find the first wrong line In a worked solution, find the first line where the answer changes. · 8 min
- 13 Checkpoint Five quick checks on the later ideas. · 5 min
- 14 The big picture Twelve ideas, tied back together. · 5 min
- 15 Track quiz Cheat-sheet table plus a reveal quiz — one question per idea. · 8 min
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