Peekaboo Hiding Game

A handful of counters, a cloth or cup, and a bit of friendly mystery. Show a number, hide some under the cloth, reveal the rest, and ask: “How many are hiding?” To answer, the child has to hold the whole in mind and work out the missing part — the seed of mental subtraction. This is the activity behind Kathy Richardson’s well-known “hiding” assessment.

  1. Count out a small number of identical counters together — start with 5 — so the child knows the total.
  2. Ask them to close their eyes or look away. Hide some under a cup or cloth and leave the rest in view.
  3. “There were 5. I can see 2. How many are hiding?” The child works out the unseen part, then lifts the cloth to check.
  4. Swap roles — let the child hide and quiz you (sometimes get it wrong on purpose; they love correcting you).
  5. Celebrate when they just know — “5 and 2… so 3 is hiding!” — rather than needing to count up.

Variation: change the total (4, then 6, up toward 10). For a harder version, hide all of them and show none (“how many under here?”), or hide some of a known 10. For an easier version, count the visible counters together first.

Requirements

  • Space: A tabletop, tray, or lap — a small contained area
  • Surface: Any flat surface; a cloth, cup, bowl, or hand serves as the hider
  • Materials: 5–10 identical counters (cubes, coins, buttons, pebbles) and an opaque cup, bowl, or cloth to hide under
  • Participants: 1 adult and 1 child taking turns hiding and guessing
  • Supervision: Light for 5-year-olds; close with small counters near children who mouth objects

Rationale & Objective

The hiding game targets the hardest and most valuable idea in early operations: that a number is made of parts, so if you know the whole and one part you can find the missing part — a missing-addend problem, which is subtraction in disguise (Common Core K.OA.5 fluency, and the unknown-addend thinking running through K.OA). Kathy Richardson built her Hiding Assessment (part of Developing Number Concepts) around exactly this task because it reveals whether a child knows the parts of numbers to 10 without counting — the marker of true fluency rather than rote recall. Because the hidden counters can’t be counted, the child must reason from the whole, pushing them off “count all” and toward mental strategies and number-fact recall.

Progress Indicators

  • Early: can’t yet find the hidden part without seeing it; guesses, or needs to uncover and count to know
  • Developing: works out the missing part by counting up from what’s visible (“2… 3, 4, 5 — three hiding”), reliably for totals to about 5
  • Proficient: quickly states the hidden part for many totals to 10, often without visibly counting; knows the parts of 5 and several parts of 10 by heart
  • Advanced: instantly knows the missing part for any total to 10 (“7, I see 4, so 3”), and can do it with the whole set hidden — pure recall of number parts

Safety Notes

  • Counters are small parts — supervise closely and tidy away from children who still mouth objects (choking hazard)
  • Use a soft cloth or lightweight cup as the hider; nothing heavy that could be dropped on fingers
  • Keep the challenge within reach — if every round needs uncovering to count, drop to a smaller total so the child can succeed and stay engaged

Hints

  • Playfulness: give the cup a name (“the mystery pot”), add a magic word before the reveal, and act amazed when they’re right; pretend not to know and let them teach you
  • Sustain interest: vary the total and who hides; theme the counters (“sleeping bunnies” in a burrow); a few rounds at bedtime or bath becomes a ritual
  • Common mistake: always letting the child uncover and count before answering — that skips the thinking. Ask for the guess first, then lift the cloth to check. Also, jumping to 10 before 5 is solid
  • No equipment: hide counters under a hand, pebbles under a leaf outdoors, or fingers behind your back; anything opaque works
  • Cross-domain: the suspense builds working memory and attention; taking turns and catching your deliberate mistakes builds social confidence and self-regulation
  • Progression: total of 4–5, count up to find the part → totals to 10 → answer before checking → hide the whole set (no part visible) → recall instantly without counting

Sources

  • Richardson, K. (2003). Assessing Math Concepts: Hiding Assessment. Math Perspectives / Didax
  • Richardson, K. (1999/2012). Developing Number Concepts, Book 2: Addition and Subtraction. Pearson
  • Common Core K.OA.A.5 (fluently add and subtract within 5; unknown-addend thinking)
  • Clements, D. H. & Sarama, J. (2014/2021). Learning and Teaching Early Math: The Learning Trajectories Approach (3rd ed.). Routledge
  • Head Start ELOF — Mathematics Development (P-MATH 6: addition and subtraction)
  • HighScope KDI 33 (Part-whole relations — combining and separating quantities)