Before you can teach children to identify or make their own squares and rectangles, they need to know the defining characteristics of each shape. Start with a picture of a rectangle and point out how it has four straight sides and four angles that are all the same. To compare, show a trapezoid or rhombus that has some acute and some obtuse angles. Then, show a picture of a square and say that it is like a "special rectangle" because it not only has four equal angles and four straight sides, but all of its sides are the same length.
In small groups, have the children sit around a pile of blocks made up of many shapes, including both squares and rectangles. Ask each child to pull out a square or a rectangle from the pile. If he pulls out a square when you asked for a rectangle, ask him what makes that shape a rectangle. This is a chance to explain again how squares are special kinds of rectangles. You can also do this by including other shapes for students to identify.
No matter what kind of house children live in, if you ask them to draw their house, they will often draw a basic square house with some rectangular windows and a triangular roof. To help teach shapes to students, have their draw a house or their school or some other building using squares and rectangles. Remind them that windows can be square or rectangular, but that doors tend to be rectangular only. Encourage them to use as many squares and rectangles as they can, such as a rectangular flag, a little square doghouse, or a rectangular chimney.
Create or download a bingo sheet featuring various shapes. This works best if you're teaching squares, rectangles and other shapes, too, but you can always adapt it to fit your lesson. Once every student has a bingo sheet, call out a shape and allow the students to color that shape on their sheets. Keep going until a student, or students, color in three shapes in a row, up, down or at an angle. Have a prize for the winner or a little something for everyone as soon as they finish.
Have the students look around the classroom and identify squares and rectangles they see, such as the teacher's desk, a filing cabinet, a bulletin board, and so on. You can ask for volunteers to raise their hands if they see the shapes or call on kids to find the shapes. You can always give hints if kids are stuck. As a homework assignment, ask the children to look for squares and rectangles on their way home from school and around the house.