While doing the concept of shapes, it would be better to provide children with some hands on activities so that the properties of shapes are clear to them.
For this children may be given some moulding clay and a few sticks. The teacher should then mould the clay into small balls and join them with sticks to form a triangle or any other shape.
As the chidren recognise the names of he shapes, they will now be told to make the different shapes themselves. By doing this the children will see that a rectangle has 4 sides and 4 corners, and so on.