These are interactive browser demos — no compiler, no setup. Open them full-screen and show them live in class to make cache coherence and false sharing physical.
▶ Open the Interactive SlidesTwo cores, their caches, and shared memory. Click read/write and watch a copy go stale, get invalidated, and the MESI states change live.
Two independent counters on the same cache line ping-ponging vs padded onto separate lines. Watch the "same line" version run slower — the whole bug in one animation.
No installs, no compilers — these run in any modern browser. Real OpenMP / MPI / CUDA code arrives in Unit IV.