This is a tool to help students visualise the stacks in ‘Cube Counting’ spatial reasoning questions. These questions present a stack of small, cube-based 3D objects. The student is asked to work out how many objects are in the stack.

A few rules for this one: firstly, stacks are only made up of one type of piece. So, you can’t combine different pieces to construct abominations. Secondly, pieces cannot float. They must be fully supported on their base — the whole length of it. If the piece highlighter turns gray, you’d be putting a piece somewhere that would make it float.