Practice and check
Worked example
Count by horizontal layers, including covered support cubes. The printed rule says every column is filled from the base.
6 + 6 + 1 = 13
- 6 + 6 + 1 = 13
Check answers after trying
1: C 2: C 3: C 4: C 5: D 6: D
Count by horizontal layers, including covered support cubes. The printed rule says every column is filled from the base.
Why this answer
- 1: 6 + 6 + 1 = 13 → C
- 2: 5 + 5 + 5 + 1 = 16 → C
- 3: 6 + 4 + 4 = 14 → C
- 4: 10 + 10 = 20 → C
- 5: 4 + 4 + 4 + 4 + 4 = 20 → D
- 6: 9 + 6 + 3 = 18 → D
Tips for Parents
▸ Why It Matters This worksheet closes out the eight-part cube-counting series, and it's designed to demand everything the previous seven built up, all at once. Some columns here aren't just hidden behind others — they're only implied by a shadow, a sliver of an edge, or a partial view, meaning your child has to layer several inference rules on top of each other in a single puzzle: the gravity rule, layer-by-layer counting, written bookkeeping, and simple persistence when the picture refuses to give up its answer easily. No single skill from this series is enough on its own anymore, which is exactly the point — this worksheet exists to prove that the individual habits your child built one at a time can now work together as a single, flexible toolkit. That combination — knowing several strategies and being able to switch between them when one stalls — is closer to how real problem-solving actually works than any one technique alone, whether in math, science, or everyday troubleshooting. Review questions: 3 · 3D Shape Reasoning 7 - Count the Hidden Cubes (Advanced). ▸ Getting Started Slow down on purpose, more than usual. Have your child work through the pile one small region at a time rather than trying to take in the whole structure at once, marking each region as solved on scratch paper before moving to the next. Encourage them to name out loud which rule they're using for each tricky spot — "I think there's a hidden cube here because of gravity" or "this one's a shadow, so there must be something blocking the light" — since naming the rule keeps them from guessing blindly and shows you exactly where their reasoning is solid or shaky. ▸ If They Get Stuck At this level, it's completely fine — expected, even — to guess a total and then double back, recounting using a different method entirely, such as top-down instead of front-to-back, purely to see whether the two answers match. A mismatch isn't a failure; it's useful information that points to exactly where the error is hiding, and re-examining just that one region is far more efficient than starting over from scratch. ▸ Praise Points At this capstone level, effort and persistence deserve far more praise than whether the final number is correct: "You didn't give up when your first count didn't match your second one — you went back and figured out exactly where the mistake was. That's precisely how real problem solvers work, and it matters more than getting it right on the first try."
What This Worksheet Builds
This expert-level worksheet requires combining several inference rules at once, since some columns are only implied by shadows or partial views rather than shown directly — building real problem-solving persistence, not just spatial skill.
Next Step
After mastering this set, have your child try building an equally complex structure with real blocks and challenge you to count it — teaching the puzzle back is an even stronger test of mastery than solving it.