Mathematics Class 7
Expressions using Letter-Numbers
Use letters for unknown numbers, write rules and formulas, and collect matching terms.
15 lessons · ~96 min total
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Lessons in this topic
- 0 Start here A roadmap: a letter holding a number, a rule written once, putting a number in, and sorting the pieces that match. · 4 min You are here
- 1 A letter can hold a number A letter stands in for a number nobody has chosen yet, and a line built from it is called an expression. · 6 min
- 2 One rule, written once, for every step The plus-tile pattern written as 4n + 1, so any step can be answered without building the ones before it. · 7 min
- 3 What 3n really means Writing 3n instead of 3 × n is a shortening of the writing, not a change to the number. · 6 min
- 4 Putting a number in Give the letter a value and the expression stops waiting and becomes a number. · 7 min
- 5 Always, or only sometimes Two expressions that match at every value are the same expression; two that match at one value are not. · 7 min
- 6 Terms of the same kind An expression is built from terms, and only terms sharing a letter part may be gathered into one. · 7 min
- 7 Putting two expressions together Adding or taking away a whole expression, then collecting the like terms that end up side by side. · 7 min
- 8 Writing an expression for a real situation Turning a fare or a bill into one line: an amount for each one, plus an amount charged once. · 7 min
- 9 A formula is a rule in letters A formula is a rule written in letters. · 6 min
- 10 Letters in a calendar square One letter names every date in a calendar square. · 7 min
- 11 Spot the slip Put the same number into both sides. Different answers show a mistake. · 7 min
- 12 Checkpoint: formulas, calendars and slips Check formulas, calendar letters and testing a simplification. · 5 min
- 13 The big picture Eleven ideas, tied back together. · 5 min
- 14 Track quiz Cheat-sheet table plus a reveal quiz — one question per idea. · 8 min
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