While children are most likely aware that you - as their teacher or parent - are much bigger than they are, they may not realize the technical terms or range of sizes when it comes to big and little.
Introducing your students to the extreme opposites of sizes is very educational and can be fun. It will be the foundation for learning the opposites of other things, like hot or cold. Teaching preschoolers big and small is the starting place when teaching kids all about opposites.
The book “Big Little,” by Leslie Patricelli, is a terrific literary start when introducing preschoolers to sizes, big and small. The illustrations and the text are easy to understand, and the children will love seeing the drawings that illustrate the opposites in size.
This author has many customers who were happy with their choice and one had this to say:
“This is a very clever book, with comparisons such as “Ladies are big, lady bugs are little”. The illustrations are beautifully hand-painted, and kids like that they are simple, colorful and cute.” 
- Discussion - Once you have read the book to your students, spend some time discussing the concepts to assess their understanding. Have at least three sets of items that would demonstrate the comparison between big and small. For example, you may wish to use two pencils, two toy trucks, two toy dolls, two pre-cut shapes made from construction paper, or two pictures of animals that are all opposites in size. Allow them tell you which one is the big one and which one is the small one.
- Big Ball, Small Ball game - Use a hard rubber container and fill it with different size balls - like a few beach balls and some of the small colorful playroom balls. Have each child one by one go over to the container and pick up a ball. Once they have done that, ask them what size it is. Be sure to encourage them that they were almost right, even if they call the wrong size.
- Blocks - Give each child a block that is either big or small. Set aside two areas for each size block and place one block in that area for them to compare their own to. Explain that you want them to wait until they are called and when they are called, they must put their block near the one that is the same size that they have.
- Hands - You and the children can outline your hands and color them in. Once you have completed that, place your drawing up against one or more of theirs and ask them which is big and which is little.
Overall, this preschool lesson plan is a great springboard for teaching preschoolers big and small. These activities will set them on the right path for using the life-long comparison tools of big and small. You will love teaching preschoolers the difference between big and small.
 “Big Little (Board Book)”. Amazon.com. June 29, 2009 https://www.amazon.com/Little-Leslie-Patricelli-board-books/dp/0763619515/ref=sr_1_3?ie=UTF8&s=books&qid=1246256880&sr=8-3.