Q2 Decomposition

21. Computational Thinking


Joe - So Lila did you finish studying the Computational Thinking vocabulary and use the Quizlet to help the us learn the vocabulary words?

Lila - HAHA Joe, remember the two of us are in this together. One of our words is decomposition. 

Joe - Doesn't that mean that something died? 

Lila - Uh no, not in this case! In computational thinking, it means to take a complex problem and break into smaller chunks. So yeah, when something dies it rots and breaks down which is why you thought it was the same thing. But no, in this case it means it is going to be simpler to solve the problem because we broke it down. 

Joe - That's kind of like the 21things, where each Thing is broken down into smaller Quests isn't it? So I have a big history report coming up. Can I use decomposition to try and make it easier?

Lila - You sure can! There are lots of things that you have to do to write the report right? You need to sit down and write down all the things you need to do to get the report done. 

Joe - What are some things that you wrote down?

Lila - Well, I start by looking at what the problem is. For the history report it means doing some research. That includes finding websites and books to use. Then I need to know if we have to do a presentation, write a report, or make a poster. Will I be working with a partner? What is the timeline for when things are due? These are some of the ways I break the problem down.

Joe - Wow, I didn't think of all those things. It sounds like if I get more organized like you, it will be a lot easier to do my report.

Lila - I think you do this kind of thing all the time when you are with your coach and deciding what plays to make to get a  touchdown.

Joe - (excited) Yeah, we sure do break it all down. Thanks Lila, I feel better about this now.


Decomposition is the first component of computational thinking. You may have heard the word in reference to something dying or rotting. When something decomposes it does break down into something different.

In the case of computational thinking, decomposition is breaking a complex problem into smaller chunks. The problem can be as small as learning to tie your shoes or as large as constructing a new car that drives itself!

You are going to learn how to break a complex problem into smaller chunks in this Quest. 

Key Vocabulary

Decomposition: Decomposition is to break down a complex problem or system into smaller, more manageable parts.

Complex problem: Complex problems are questions or issues that cannot be answered through simple logical procedures. 

I Can Statement

  • take a complex problem and break it into smaller chunks


1. Watch as a class the video Computational Thinking: Decomposition. You will watch the first 6:25 of the video. 

2. As you can see in the video, there are complex problems that you are solving every day. 

3. With a partner you are going to do decompose and break down the tasks it will take to make homemade slime. (e.g., what is needed, what has to be purchased, costs, who is going to make it, etc.) You are not creating steps at this point on how to make it. You are looking at the big picture and what is needed to break it down into tasks. 

  • Your teacher may assign a different complex problem. 

4. Open up a Word Document or Google Doc to share with your teacher. You are going to break down the tasks into chunks so that someone reading it will know what is needed to solve the complex problem. 

5. Once you have completed this assignment, as a class you will share out how you broke down the complex problem assigned to you and your partner. 

  • If the teacher assigns the whole class the same problem, compare and contrast as a group the decomposition. 

6. Now using the Computational Thinking Document that you made a copy of in Quest One, break down your own complex problem into chunks. 

Completing This Quest

To complete this Quest turn in your decomposition activity to your teacher (via Google Drive, OneDrive, etc.). Then complete the steps for your complex problem and share with your teacher when it is completed. 

Websites and Applications

Competencies & Standards

MITECS   Michigan Integrated Technology Competencies for Students, and

ISTE Standards for Students

c. Students break problems into component parts, extract key information, and develop descriptive models to understand complex systems or facilitate problem-solving.