Every flat shape is built from straight sides that meet at corners, and math calls those corners vertices. This 3rd grade counting sides and vertices worksheet starts with a short reminder box. It shows a rectangle with one vertex and one side labelled, so the two words are clear before the counting begins. Below it, there are eight flat shapes in colour, such as an arrowhead, a cross, a triangle, an octagon and a tall rectangle. The last three are trickier, because they look like an hourglass, a house with cut corners and a letter M. Under each shape, your child writes the number of vertices and the number of sides. The page sits on light grid paper, so the lines are easy to follow. Page two is the answer key, with every number filled in.