Test each corner for a square corner (a right angle); the corner of a sheet of paper makes a handy tester. Then look for pairs of sides that never meet: they're parallel.
right anglea square corner
right trianglea triangle with one right angle
parallel sidessides that never meet
quadrilateralany shape with 4 straight sides
Watch for: Missing a right triangle that's turned so the square corner isn't at the bottom. Thinking a triangle can have two right angles. Counting a trapezoid as having four right angles because it has parallel sides.
At home: Use the corner of a sheet of paper to test corners at home: books, tiles, signs, a slice of toast.
Sample sheet and answer key
Luna's Space Adventure
Grade 4 · Classifying shapes · 4.G.A.2
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Right triangles
Circle each triangle with a square corner.
Sides and angles
Circle yes or no.
A square has perpendicular sides.yesno
A triangle can have two right angles.yesno
A trapezoid has exactly one pair of parallel sides.yesno
A rhombus always has four right angles.yesno
A rectangle has two pairs of parallel sides.yesno
Right angles
Circle each shape with four right angles.
Sheet
Luna's Space Adventure
Grade 4 · Classifying shapes · 4.G.A.2
Answer key
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Right triangles
Circle each triangle with a square corner.
Sides and angles
Circle yes or no.
A square has perpendicular sides.yesno
A triangle can have two right angles.yesno
A trapezoid has exactly one pair of parallel sides.yesno
A rhombus always has four right angles.yesno
A rectangle has two pairs of parallel sides.yesno
Right angles
Circle each shape with four right angles.
Answer key
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
