This heatmap visualizes the relationship between per-pupil spending and graduation rates across Massachusetts schools, using data from the MA_Schools.csv dataset. It shows patterns of density through color intensity, with orange-to-red hues indicating higher concentrations of schools at specific spending and performance combinations. The visualization uses D3 v7 to bin data points into a 20×15 grid, then renders SVG rectangles colored via a sequential scale (d3.scaleSequential with interpolateOrRd). Interactive tooltips appear on mouseover, while axes display spending in dollars and graduation rates in percentages, with a legend implied by the color gradient.