Drag rhythmic values into up to 8 beat blocks per line to build a drum groove, or click a tile then click a block to place it — handy on a trackpad.

🎵 Grade 1 Lesson 20: Adding Within 100 — Add Within 100 (1.NBT.C.4) mess around all you want, nothing here saves
86 BPM
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🎯 Lesson: 0/4 · 🥁 0 solved · 0 badges

Grade 1, Lesson 20: Adding Within 100

Math skill: Add Within 100 (1.NBT.C.4)

How the beat teaches it: Every slot adds a small number onto a two-digit number — the tens never move, so just build the new ones total.

This is lesson 20 of 24 in RockBlocks Math, Grade 1, a free course where every lesson turns a math idea into something you can count, hear, and play. The previous lesson, Comparing Two-Digit Numbers,” covered comparing Numbers (1.NBT.B.3). Next is Lesson 21, Measuring Length with Units.”

Every slot above (A, B, C, D) is its own question, and it’s a real, blank RockBlocks beat the whole time — the same drag-and-drop tiles, kit, tempo, sheet music, and drummer view as anywhere else on the site. Tap ❓ Questionin the corner to read the current slot’s problem, build your answer right in the grid, then tap ✓ Check Answerto grade it. Once you’re done, keep going: expand the beat, drop it into a Stack, or save a copy to your own page — nothing here overwrites the lesson itself, so every visitor still starts from the same blank slots.