Show students how to combine rectangles and triangles to create houses.
The opposite sides of a rectangle are parallel.
A square is always a rectangle, but a rectangle is not always a square.
A square is one type of rectangle.
Every square is a rectangle. A rectangle has four right angles.
rectangle - a shape with four sides and four angles of 90 degree
English word "长方形"(rectangle) occurs in sets:颜色和形式 - Colours and shapes