Angle, right angle, rectangle and square
Name an angle by letters, find a right angle with the model, tell a rectangle from other quadrilaterals and a square from other rectangles.
- Ukraine: grade 2
- Russia: grade 2
Guide
In Ukrainian Grade 2 an angle is made by two rays with a common start. The rays are the sides of the angle and their common start is the vertex. An angle is named by three letters with the vertex letter in the middle: ∠ABC.
A right angle is made by folding a sheet of paper twice. All right angles are equal. To test an angle, put the model of the right angle or a set square on it. An angle may be bigger or smaller than a right angle. A right angle is marked ⌞.
A rectangle is a quadrilateral whose angles are all right angles. Its opposite sides are equal. A square is a rectangle whose sides are all equal, so every square is a rectangle but not every rectangle is a square.