155 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 a 3x3 Determinant by Cofactor Expansion
How the beat teaches it: Every slot gives a 3x3 matrix — expand along the first row: det = a(ei−fh) − b(di−fg) + c(dh−eg) for matrix [[a,b,c],[d,e,f],[g,h,i]]. Build that many notes anywhere in the kit.
This is lesson 6 of 24 in RockBlocks Math, Linear Algebra, a free course where every lesson turns a math idea into something you can count, hear, and play. The previous lesson, “Matrix Transpose,” covered find an Entry of a Matrix's Transpose. Next is Lesson 7, “Inverse of a 2x2 Matrix.”
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.