Tear a copy of each remote interior angle and fit it into a triangle's exterior angle — the two stack flush, so exterior = remote + remote is something you see, then dial the one unknown.
Every interior angle of the triangle is a wedge you can tear a copy off; drop the two remote interior wedges into the dashed exterior angle and they stack flush against its far ray, so the exterior angle theorem is seen rather than recited, while the adjacent interior angle sits there as a live decoy that visibly overflows when fitted. Solve rounds give the exterior angle and one remote and ask you to fit the known one and dial the missing one; parallel-line rounds draw a line through the apex so you fit each top wedge onto its alternate-interior partner and dial the apex angle to close the straight-line 180°. It targets the 'exterior = 180 − adjacent only' habit and the swapped Z-angle pairing. Best for Grade 8.
A free, no-signup, no-ads math game for Grade 8 — practising exterior-angle, triangle-angles, parallel-lines, alternate-interior-angles, missing-angle. Play in your browser on the KidsDoMath games hub or explore more Geometry & Shapes games.
By grade level: 8th Grade Math Games
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What math does Exterior Angle Express practice? Exterior Angle Express practices Exterior Angle, Triangle Angles, Parallel Lines, Alternate Interior Angles. Every interior angle of the triangle is a wedge you can tear a copy off; drop the two remote interior wedges into the dashed exterior angle and they stack flush against its far ray, so the exterior angle theorem is seen rather than recited, while the adjacent interior angle sits there as a live decoy that visibly overflows when fitted.
What grade is Exterior Angle Express for? Exterior Angle Express is built for Grade 8 (ages 13–14). It sits in the Geometry & Shapes strand, and it ramps across 8 levels so younger or older players find their own pace.
How do you play Exterior Angle Express? Tear a copy of each remote interior angle and fit it into a triangle's exterior angle — the two stack flush, so exterior = remote + remote is something you see, then dial the one unknown.
Is Exterior Angle Express free to play? Yes. Exterior Angle Express is free, with no ads and no sign-up, and it runs in the browser on a phone, tablet or computer.