Match the opening
Choose the opening the whole solid can pass through.
Continue your unfinished round
Your answers are saved in this tab. Continue from where you left off.
Continuing uses no additional practice start.
Discard the unfinished round?
Your answers from this round will be discarded. You can choose your settings before starting a new round.
Starting the new round uses one practice start.
Study the solid. Choose the opening it can pass through.
More height changes
6 questions · No time limit
Your last settings are ready. Change them whenever you like.
Example
Example
Start to get six puzzles.
- Questions answered
- 0 / 6
- Active time
- 0:00
Which opening fits the whole solid?
Study the solid. Choose the opening it can pass through.
Turn in 90° steps around the arrow first, then slide straight.
Every stack is solid from bottom to top.
Start to get six puzzles.
Optional and off by default. Share starts, completions, replays and error categories. For visits from ChatGPT, starts and completions can also include the first QuickenBrain page and broad country. No answers, drawings or names.
How this data is usedHelp
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 five 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 1–5 also select openings while answering, except when another control is focused. This is a visual practice; the figures require sight.
About this practice
Learn a method
Project the whole solidChoose the opening the whole solid can pass through.
Report a problem
Optional and off by default. Share starts, completions, replays and error categories. For visits from ChatGPT, starts and completions can also include the first QuickenBrain page and broad country. No answers, drawings or names.
How this data is used