Learn · Illustrative Mathematics K–5 · Grade 4 · Unit 4
Short lessons you can play with. Write tenths and hundredths as decimals, build numbers up to 1,000,000, compare and round them, and add and subtract with the standard algorithm, then check yourself.
Seven 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.
Decimals go to hundredths and come with hundred grids and money or measurement stories. Whole numbers go up to 1,000,000 with only a few nonzero digits. Each problem for adding or subtracting in columns needs at most one regroup, except the ones about zeros, where regrouping across the zeros is the point.
Decimal: a way to write tenths and hundredths, like 0.47 for 47/100. Place value: what a digit is worth because of its place: the 3 in 305,020 is worth 300,000. Round: find the nearest multiple of 1,000, 10,000, or 100,000. Standard algorithm: adding or subtracting one place at a time in columns. Regroup: trade 10 of one unit for 1 of the next (or back).
Bees are Buzzing (Lesson 23) is an optional lesson. Practice it all in Rocket Lab, the game for this unit.