Show children pictures of circles and triangles. Use three-dimensional plastic circles and triangles so that children have objects to hold. Discuss what makes a circle a circle, such as its round shape, or what makes a triangle, such as three sides and three points. Allow children to handle the plastic shapes and use them in conjunction with toy blocks or other education enhancing toys.
Read a shape book together after reviewing the three-dimensional and two-dimensional shapes. While reading the book, trace the circle with a finger and point out the lines in the triangle. Show children pictures of natural objects that are circles and triangles such as the moon, a slice of pizza or a pointed hat.
Take the children on a shape finding adventure. Lead children in a march around the room or building to find the shapes. Point out circles and triangles occurring naturally in the classroom and learning environments. Encourage children to do the same and start a list of their finds or bring objects to a central table. When children are finished exploring, discuss the lists or review the objects as a class.