144 BPM
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4/4 ×2
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.
Math skill: Find the Sum of Vertex Degrees From the Edge Count
How the beat teaches it: Every slot gives a graph's number of edges — the handshake lemma says the sum of every vertex's degree equals 2 times the number of edges, since each edge touches exactly two vertices. Build that many notes anywhere in the kit.
This is lesson 15 of 24 in RockBlocks Math, Discrete Math, a free course where every lesson turns a math idea into something you can count, hear, and play. The previous lesson, “The Pigeonhole Principle,” covered find the Minimum Items Needed to Guarantee a Repeat. Next is Lesson 16, “Edges in a Complete Graph.”
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.