Congratulations to Alistair S. of the 3rd grade, Julia B. of the 4th grade, and Hudson Cooke of the 7th grade for using toothpicks of equal size to construct the double tetrahedron that contains 7 triangles and going on to find the 4D tetrahedral shape by placing a fifth marshmallow at the center of the tetrahedron, and connecting it to each of the original 4 marshmallows with shortened toothpicks so as to make 10 different triangles.