Close the open corner — dial the missing angle so a triangle sums to 180° or a quadrilateral to 360°.
One corner of a triangle or quadrilateral is open, and the child dials the missing angle so the angles sum to 180° or 360°, with a meter stacking the known angles toward the total. Using the angle-sum rule builds geometric reasoning. Best for Grade 6.
A free, no-signup, no-ads math game for Grade 6 — practising angle-sum, triangle-angles, quadrilateral-angles, missing-angle, supplementary. Play in your browser on the KidsDoMath games hub or explore more Geometry & Shapes games.
More like this: Circle Lab · Transformer Grid · Volume Vault.