Learn · Illustrative Mathematics K–5 · Grade 2 · Unit 7
Short lessons you can play with. Jump by hundreds, tens, and ones, add and subtract by place, make a new ten or hundred, and break a ten or hundred to subtract, then check yourself. Tap Read to me to hear any step read aloud.
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.
The Read to me buttons read each step and quick check aloud with the device’s built-in voice, for students still learning to read. Progress is saved on this device.
All numbers are within 1,000, shown with base-ten blocks (a big square is a hundred, a stick is a ten, a small square is a one) and open number lines, which show jumps but aren’t drawn to scale. Quick checks that ask for an answer need at most one new ten or hundred, or one broken ten or hundred. Problems that need two trades (Lessons 9 and 15) are done with blocks one trade at a time, and their quick checks ask what needs to happen instead.
Add and subtract like units: hundreds with hundreds, tens with tens, ones with ones. 10 ones make a ten and 10 tens make a hundred, so a ten or a hundred can be traded when there are too many or too few. Before subtracting, look at the numbers: if they’re close, counting on is often quicker.
Center Days (Lessons 5, 11, and 17) and Paint Splattered Bar Graph (Lesson 18) are optional lessons that work better in class. There’s no practice game for this unit yet.