Apply math concepts to scale down the planets 100 million times smaller than their real sizes. Students follow 4 simple steps to scale down planet diameter and radius. Students use tools like a bullseye compass or a regular metric ruler to create the 2D models on paper. Math concepts include metric unit conversion (km to cm), parts of a circle (radius and diameter), scale modeling, measurement, and rounding. This activity works great for math or science. A one-page printable template for the inn