One-difference Classification Train

Math Lesson Plan

Students will learn how one can group things in various ways. They will be able to distinguish between things that are different in only one way and things that are different in more that one way. Students will be able to manipulate individual pieces of the classification kit in order to form a "one-difference" train.

classification kit


  1. Guess my rule: Pick students one by one to form groups based on differences. For example: boys/girls glasses/no glasses short/tall, etc. Students have to figure out what rule you are grouping them by.
  2. Discuss the concept of grouping in general. Let children experiment with the kit and discuss the idea of some of the pieces being different in only 1 way, some in two ways, and some in even more ways.
  3. Lay out all of the pieces in the kit and explain the rules of making a "one-difference" train. This is a "train" of pieces from the classification kit laid out in such a manner that adjacent pieces have only 1 differing attribute. For example: thin red circle--thin red triangle--thick red triangle--thick blue triangle--thick blue square.
  4. Have students take turns laying pieces, making sure the entire group agrees before continuing.
  5. Play until students have used up all pieces.

Ask students questions: What other ways can you think of grouping us that we haven't already used? What other things can you think of grouping?

Notice how well students are able to find pieces that are different in only one way. What kind of problems do they have? Which attributes do they recognize the easiest? Which the hardest? Are they able to think of instances in real-life where they can group?

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