Infer the total cubes in a pictured structure, including supported hidden cubes.
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Practise it now
Some cubes are buried where you cannot see them. Spin the model and work out how many are hidden.
It covers most of this skill rather than all of it.
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A worked example
One question of the kind this skill is tested with, worked all the way through: the reasoning, and what the wrong answers are there to catch.
Finding the buried cubes
This stack is built from 34 cubes standing on 16 squares. A hidden cube is one that is completely boxed in, so you could not see it from any side. Work along the stack and find them.
3 cubes in this stack are walled in on all four sides with a cube on top, so they are hidden.
6
3
4
5
Answer: 3
How you get there
The stack holds 34 cubes. A cube is hidden only when a cube sits on top of it and a cube sits in all four places beside it, because the table already hides its base. Checking the columns away from the edges level by level finds 3 cubes boxed in like that, so the answer is 3.
Why the other answers tempt
A cube at the back of the stack is not hidden. You could walk round and see it, so it does not count.
If they are stuck, say this
Take one column at a time. A cube in that column is hidden when there is a cube above it and a cube in each of the four columns beside it at the same level.
Some cubes are buried where you cannot see them. Spin the model and work out how many are hidden.
Counting a solid means counting what you cannot see. This model has 15 cubes in total and 1 of them are completely buried - a buried cube has cubes on all four sides of it and a cube on its roof, and its base is flat on the table, so no face of it is left showing however far you spin the model. Work stack by stack from the plan, never from the picture alone.
What to say if they get stuck
Drag to spin the whole model right around. If you can spot a cube from ANY side, it is not hidden.
A cube is hidden when it is walled in on all four sides with another cube on top of it. Only the plan grid can prove it.
Count every cube first, then count the ones you can actually see. The gap between them is the hidden pile.
Counts only visible cubes where support implies hidden cubes.
This is the wrong answer 11+ papers are built to offer, so it is worth watching for directly: a child who does this will look confident and still lose the mark. If it keeps happening on count cubes in a structure, the fix is the misunderstanding rather than more questions.
Questions parents ask about count cubes in a structure
Answered from what the skill map records about this skill, not from a template. Every answer here is on the page, and the same questions are the page's FAQ structured data.
Infer the total cubes in a pictured structure, including supported hidden cubes. It is one of 22 named non-verbal reasoning skills in the 11+, in the spatial strand, and this page carries 1 interactive exercise that practises it.
There is a specific mistake recorded against this skill: counts only visible cubes where support implies hidden cubes. 11+ papers are written to offer exactly that answer, so a child can be confident and still lose the mark. When it keeps happening, the fix is the misunderstanding rather than more questions.
Point at the next move rather than explaining the whole rule. Take one column at a time. A cube in that column is hidden when there is a cube above it and a cube in each of the four columns beside it at the same level.
The skill map draws the line here: Assume stability only when the representation requires it. A question past that line is testing a different named non-verbal reasoning skill, which is worth knowing before you spend a week practising the wrong one.
The spatial strand holds 8 skills that are tested together, and the pages next to count cubes in a structure are find an embedded shape, match a solid and its view and rotate a 3D solid mentally. Each has its own exercise and its own link, and none of them needs an account.
Use Block Builder, embedded on this page. It is the exercise the skill map attaches to count cubes in a structure, it runs in the browser with no account to make, nothing is scored, and nothing a child does here is recorded or sent anywhere. It also has its own link, so you can send it to a child without sending them anywhere else first.
One wrong answer is a slip, the same wrong answer every time is a habit
A free diagnostic looks at which mistakes repeat across all four subjects, not just whether count cubes in a structure was right on the day.
