When choosing materials to use when teaching sizes, we need to think about some important things. First,when we first are introducing the concept, the items need to be identical except for the feature we want our learners to discriminate, which is size. Some learners will overgeneralize or memorize a label you teach with a certain material by attending to a feature of that material not related to the concept you are teaching. An example would be if you had a big rock, a medium size leaf and a smaller acorn and used these to teach sizes to a learner new to the concept. A special learner might not see size as the attribute to be discriminated- there are so many differences in these items- texture, color, shape etc. A second thing is that size is relative. Big can become medium when compared to something larger. Small can become big when compared to something smaller.
I created a free set of materials to help you overcome these obstacles! This resource has 10 sets of items in 4 sizes to use any way you wish in teaching of size. There are 4 sizes so the little ones can become medium and the medium can become large, etc)
Suggestions for use: a. Receptive and Expressive Identification of Big/Large, Medium, Small/Little. b. Using size words to describe: big apple, little spider etc. c. Comparatives and superlatives for sizes (big bigger biggest, etc) d. Games with the associate items sets: (put the little apple on the big tree, put the big spider in the medium web, put the big train on the little track etc.) e. Match up associated items by size (little ice cream scoop to the little tree, big apple to the big tree, medium spider to the medium web, etc) f. Put the items of each set in order according to size. https://www.teacherspayteachers.com/Product/Size-Printables-Freebie-Small-Medium-Large-Big-Little-Games-5077157