Lesson 28: Crowdsourcing


In computer science, we face some big, daunting problems. Challenges such as finding large prime numbers or sequencing DNA are almost impossible to do as an individual. Adding the power of others makes these tasks manageable. This lesson will show your students how helpful teamwork can be in the industry of computer science.


It's very rare that one computer scientist works completely alone on a project. Even when that does happen, there is always benefit in numbers. Today, students will learn what it means to crowdsource a project. This activity builds teamwork and creates an efficient environment for students to solve problems.


Warm Up (20 min)

Main Activity (20 min)

Wrap Up (15 min)

Extended Learning

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Students will be able to:

  • Identify a large task that needs to be done.
  • Rearrange a large task into several smaller tasks.
  • Build a complete solution from several smaller solutions.



Heads Up! Please make a copy of any documents you plan to share with students.

For the Teachers

For the Students


  • Crowdsourcing - Getting help from a large group of people to finish something faster.


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Teaching Guide

Warm Up (20 min)


This lesson has one new and important word:

Crowdsourcing - Say it with me: Crowd-sore-sing

Getting help from a large group of people to finish something faster.


Lesson Tip

Jars of buttons and pennies work nicely, but if you find yourself with little time to prepare, you can cut slips of paper and put them in a ziplock bag or even a pencil box.

  • Show your students your jar full of something.
    • "Look at this jar. I have a lot of buttons in here, and I need to tell the principal how many there are before the end of class."
    • "Can you think of a way I could get these counted quickly?"
  • Your students may guide you toward seeking help, but if they don't, you can suggest it, too.
    • Pour all of the buttons (or pennies, etc.) into a pile on the floor.
    • Invite all of the students to come up and grab a small number (ten is good, but you can do more if your students can handle it).
    • Once they've counted out their ten, have them report to you, drop their buttons back in the jar, and go again until the pile is gone.
  • Comment on how fast the task went.
    • Have the class reflect on how long it might have taken or how hard it may have felt to do alone.

Main Activity (20 min)

Crowdsourcing - Slides

Sometimes you have a big job that needs to get done, but it feels like it will take forever. Crowdsourcing is a way of using teamwork to make the job go much faster! In this game, we’ll use crowdsourcing to sort decks of playing cards.


Lesson Tip

It can be challenging for students to figure out how to break apart large tasks at first. Students might find it helpful to have some ideas handed to them after working for a while. One great division for sorting cards is as follows:

  • One person picks up the cards and determines the suit of each one.
  • One person manages Hearts.
  • One person manages Diamonds.
  • One person manages Clubs.
  • One person manages Spades.
  • (If there's another, they can put all sorted suits back together again.)
  1. Divide into groups of 4, 5, or 6.
  2. Grab your deck of playing cards and dump it into a bag, bucket, or even a loose pocket that you can make with the bottom of your shirt.
  3. Shake the cards until they’re all mixed up.
  4. Dump the cards out onto a table or desk where the whole group can see them.
  5. Decide how to break up the task of sorting the deck so that every person has something to do and no one is doing too much.
  6. Time yourself sorting the cards. Can you figure out a way to do it faster?
  7. Repeat the game over and over until you think you have found the fastest way of crowdsourcing the card sorting activity.

Wrap Up (15 min)

Flash Chat: What did we learn?

Lesson Tip

Flash Chat questions are intended to spark big-picture thinking about how the lesson relates to the greater world and the students' greater future. Use your knowledge of your classroom to decide if you want to discuss these as a class, in groups, or with an elbow partner.

  • Have you ever tried to sort a pile of cards by yourself?
  • Do you think it was easier or harder to have help?
  • What other things do you have to do in life that could be easier with help?


Having students write about what they learned, why it’s useful, and how they feel about it can help solidify any knowledge they obtained today and build a review sheet for them to look to in the future.

Journal Prompts:

  • What was today's lesson about?
  • How do you feel about today's lesson?
  • What are the benefits of crowdsourcing?
  • What kind of things do you want to make with computer science? How do you see crowdsourcing being beneficial in those projects?

Extended Learning

Use these activities to enhance student learning. They can be used as outside of class activities or other enrichment.

Reverse Crowdsourcing

Often we think of crowdsourcing as pulling things apart to make them more simple. You can also make big, beautiful things with the same technique.

Have your students each grab three cards and build one segment of a card house. Each student can go one after another to build a grand card tower.

Try with two, or even three students adding their chunk at a time.

  • Does crowdsourcing always make a task easier?

Crowdsourcing in the Round

  • You can crowdsource all at the same time or you can do it one person at a time. Try having the whole class sort the same deck of cards, one student at a time.
    • Shuffle the cards and place them in a pile in the center of the room.
    • Have each student approach the pile and choose four cards.
      • Have four piles for the students to sort their cards into
        • Spades
        • Clubs
        • Hearts
        • Diamonds
      • Once all cards have been put in their four piles, have the following four students sort the individual piles.
      • The last person will put all four piles together.
  • This version may not save a lot of time, but it still divides the work and lets each individual have more free time!
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Student Instructions

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Student Instructions

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Student Instructions

Standards Alignment

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CSTA K-12 Computer Science Standards (2017)

AP - Algorithms & Programming
  • 1B-AP-11 - Decompose (break down) problems into smaller, manageable subproblems to facilitate the program development process.

Cross-curricular Opportunities

This list represents opportunities in this lesson to support standards in other content areas.

Common Core English Language Arts Standards

L - Language
  • 4.L.6 - Acquire and use accurately grade-appropriate general academic and domain-specific words and phrases, including those that signal precise actions, emotions, or states of being (e.g., quizzed, whined, stammered) and that are basic to a particular topic (e.g
SL - Speaking & Listening
  • 4.SL.1 - Engage effectively in a range of collaborative discussions (one-on-one, in groups, and teacher-led) with diverse partners on grade 4 topics and texts, building on others’ ideas and expressing their own clearly.
  • 4.SL.6 - Differentiate between contexts that call for formal English (e.g., presenting ideas) and situations where informal discourse is appropriate (e.g., small-group discussion); use formal English when appropriate to task and situation.

Common Core Math Standards

MP - Math Practices
  • MP.1 - Make sense of problems and persevere in solving them
  • MP.2 - Reason abstractly and quantitatively
  • MP.6 - Attend to precision
  • MP.7 - Look for and make use of structure
  • MP.8 - Look for and express regularity in repeated reasoning

Next Generation Science Standards

ETS - Engineering in the Sciences
ETS1 - Engineering Design
  • 3-5-ETS1-1 - Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.