Cross Sections of Polyhedra
Cutting three dimensional shapes and looking at the possible shapes of the cross section.
Polygons in Polygrams
Each regular polygram has a regular polygon at its center.
Halfing 3D Shapes
Cutting 3D shapes parallel to the base such that the top and bottom resulting portions have the same volume.
Apothem of a Regular Polygon
Is this method of constructing a regular polygon an approximation? or theoretically accurate?
Chicken and Egg
Separating egg-laying chickens from non-egg-laying chickens by keeping them in boxes.
Exact Change
Counting the number of ways to make an exact amount using Canadian coins and bills.
11. 不快乐王子（上）
“等等，你怎么又写我死掉的故事？”灰灰生气地说。 “啊，真的！一不留神就又选了这样的故事。”小丹不好意思地挠了挠脸。“不过别急，这个王子还是这个故事的主角呢。”