135 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: Compute Var(X) for X = a or b, Each With Probability 0.5
How the beat teaches it: Every slot gives two equally-likely outcomes a and b — for a fair 2-point variable, the variance simplifies to ((a-b)/2)². Build that many notes anywhere in the kit.
This is lesson 6 of 24 in RockBlocks Math, Probability, a free course where every lesson turns a math idea into something you can count, hear, and play. The previous lesson, “Expected Value of a Discrete Random Variable,” covered compute E[X] = Σ x·P(x). Next is Lesson 7, “Counting Favorable Sequences for a Binomial Setup.”
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.