Composing and Decomposing with Decimals

Written by Donna Boucher

Donna has been a teacher, math instructional coach, interventionist, and curriculum coordinator. A frequent speaker at state and national conferences, she shares her love for math with a worldwide audience through her website, Math Coach’s Corner. Donna is also the co-author of Guided Math Workshop.

Arcademics Skill Builders is a fabulous FREE website with online arcade-style games for practicing a variety of skills for many different subject areas. Part/whole thinking is such a big deal, so I was thrilled to find a game for composing and decomposing with decimals. The fact that Hungry Puppies (link at the bottom of the post) is a multiplayer game (as many of Arcademics’ games are) adds a nice bit of competition. The goal is to click on bones that, when added together, equal the target sum. So, in the game pictured below, you could click on 3.1 and 0.8, because their sum is 3.9.

It is addicting!! Enjoy. 😀

composing and decomposing decimals
Here’s the link to Hungry Puppies.


  1. julie

    Like a lot of games and apps out there, we are putting students in a timed situation where they are stressed and not able to really think and reason. Research states clearly that math is not about being fast.

    • Donna Boucher

      I am in 100% agreement with you that math is not about being fast. Reasoning, critical thinking, and justifying are are cornerstones of math, but automaticity with facts is essential. We build an understanding of facts using a strategy based instruction, but practicing does build automaticity. The more fluent students are with basic facts, the more mental energy they can use for higher order tasks. It’s kind of like memorizing sight words so reading is not such a challenge.

      • Nicole

        Well written!


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