Just how many triangles are in this Christmas tree? A fun math and visually challenging activity - counting triangles within a shape of triangles! Can be used as a "What now?" activity for those that are finished with their work, or as a center activity, or a small group or pairs activity. As an added challenge, have the students draw in the lines at the bottom the complete the largest triangle, extend the inside lines, and see how many more triangles were created with just a few added lines.