Match the opening

Choose the opening the entire solid can pass through. The arrow gives the direction of travel. Every stack is filled from the bottom to its visible top.

Your answer locks when selected. The full outline appears in a matching position, with the number of clockwise quarter-turns measured while looking along the arrow. Read the explanation, then choose Next question.

View openings along the arrow, from the solid’s side. Choose a 90° turn before moving, then slide straight without tilting or twisting. Reflecting or resizing is not allowed. Include all depths, not just one end or one slice. All four openings have the same area; their shape decides the answer.

Finish all six questions to save a result on this browser. Leaving early saves no completed round. Active time counts only while this page is in the foreground; there is no time limit or speed bonus.

Use Tab and Enter or Space to select an opening. Keys 1–4 also select openings while answering, except when another control is focused. This is a visual practice; the figures require sight.