This visualization shows the relationship between per-pupil spending and high school graduation rates across Massachusetts schools. It uses a binned heatmap to display the density of schools within specific spending and performance ranges, where darker blue colors indicate a higher concentration of schools. The chart is built with D3.js (v7), using `d3.csv` to load data, `d3.scaleLinear` for axes, `d3.scaleSequential` with `interpolateBlues` for the color scale, and custom binning logic to aggregate data points into rectangles. Tooltips display the exact counts and ranges on hover. Data comes from the MA_Schools.csv file.