Learn · Illustrative Mathematics K–5 · Grade 4 · Unit 1
Short lessons you can play with. Hop along number lines to find multiples, build rectangles to find factor pairs, sort primes from composites, and solve the Locker Problem, then check yourself.
Five short chapters follow the unit’s lessons in order. Each step shows one idea with something to tap or move, then a quick check. A wrong answer names the likely mistake and gives one more try. Progress is saved on this device.
Everything stays within 100, as in the unit. Factor pairs come from arranging tiles in equal rows, so a factor pair is the two side lengths of a rectangle.
Multiple: what you land on counting by a number from 0. Factor pair: two whole numbers that multiply to make a number. Prime: exactly one factor pair (1 and itself). Composite: more than one. The number 1 is neither.
Multiplication Practice (Lesson 4) and Mondrian’s Art (Lesson 8) are optional lessons. Practice it all in Factor Factory, the game for this unit.