Density and cleanliness are the same coin
Every Wi-Fi signal carries data by setting a wave's amplitude and phase to one of a fixed set of patterns — the constellation. 'Higher QAM' means more patterns packed closer together, so each transmission carries more bits. The catch is geometric: the closer the points, the less noise it takes to mistake one for its neighbour. This lab lets you turn a noise/SNR dial and watch each ideal point bloom into a fuzzy cloud, with the carrier wave drawn for individual symbols so you can see what a 'point' actually is.
When a cloud spills across a decision boundary into a neighbour's region, that's a symbol error — and the lab counts them live alongside the EVM and the SNR each order needs. It makes the minimum-distance argument visible instead of asserting it, and turns 'why am I not getting the rated speed?' into something you can see: high-order QAM simply isn't available unless the air is quiet and you're close.