Lesson 7: Storage


Question of the Day: Why is storage an important part of the computing process?

This lesson introduces the final component of the unit's model of computing: storage. After trying out an "outfit picker" app, students discuss what information should be stored in the app versus input every time the app is run. They then look at a series of apps and use their decisions about what should be stored to create guidelines for deciding what information to store. They then review the four components of this chapter's model of computing: input, output, storage, and processing. Afterwards, they have one last opportunity to revise their decisions about which items should be classified as a "computer" from earlier in the chapter. The lesson ends with a reflection on their own app ideas and how storage could be used.


In Chapter 1 of this unit, students learned the problem solving process. In Chapter 2, students learned how computers solve problems. At this point, students know that computers are information processing machines that can do four things with information: input, output, store, and process. In this final lesson before the unit project, students look at types of input that may be needed to solve a particular problem and describe the processing and storage that a computer would do to produce the desired output. This should prepare them to eventually design their own app to address a problem and explain how that app would work.

Assessment Opportunities

  1. Determine whether some input should be stored or not.

    In the activity guide, check student answers and reasoning for what information should be stored.

  2. Identify guidelines regarding which kinds of input should and should not be stored.

    Check the guidelines that each group writes together.

  3. Use the IOSP model to identify some of the input, output, storage, and processing used in a given computer.

    The two journal prompts after the IOSP video ask students to identify the different parts of IOSP in an app they commonly use and in a smartphone.


Lesson Modifications

Warm Up (5 min)

Activity (20 min)

Introducing the IOSP Model (20 min)

Wrap Up (5 min)

View on Code Studio


Students will be able to:

  • Determine which information in a computing problem should be stored for later use.
  • Identify guidelines regarding what information should and should not be stored as part of the computing process.
  • Use the input-output-storage-processing model to describe a computing process.


  • Print a copy of the activity guide for each student


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

For the Teachers

For the Students


  • storage - saving information to use in the future

Teaching Guide

Lesson Modifications

Attention, teachers! If you are teaching virtually or in a socially-distanced classroom, please read the full lesson plan below, then click here to access the modifications.

Warm Up (5 min)

Content Corner

Students may identify the weather, favorite color, or season as the input, and the pictures of outfits as the output. Although the exact processing of the app may not be clear, students may point out that there are several likely if/then scenarios ("If the weather is rainy, then include an umbrella.") or matching between the user's input and features of the outfits.

Discussion Goal

While it's not important that students agree on the answers, this discussion introduces them to the idea of storing information for later and prompts them to think about what information should and should not be stored in an app.

Analyzing an App (Outfit Picker)

Journal Prompt: Go on Code Studio to look at the outfit picker app. What is one input, one output, and one kind of processing it might use? Let’s say you used this app every day. What information would you want this app to remember?

Circulate: The first part of this reflection serves as a review of input, output, and processing. As students reflect on the prompt, check their answers to ensure that they understand how input, output, and processing are used in the app.

Ask students to share out what information they thought should be stored and why.


This example app asks for some information that won't change very often, such as your favorite color. Instead of being required to enter this data every time, it would be helpful if the app could remember our answers by storing it. All computers can save information for later and read saved information through storage.

Key Vocabulary: Storage - saving information to use in the future

Question of the Day: Why is storage an important part of the computing process?

Activity (20 min)

Apps with Storage


We're going to look at a few apps that use a few kinds of information. We want to identify which information could be stored so that we don't have to enter it every time.

Group: Put students in groups of 2-3. Each group will need access to one computer for this activity.

Distribute: Give each group one copy of the activity guide.

As a class, complete the first section of the activity guide, which references the outfit picker app used in the warm up.

Send students to Code Studio to see the sample apps.

Assessment Opportunity

There is some flexibility about what should and shouldn't be stored, since that is a choice that the app designer could make. The most important part is their explanation. They should be reasoning about whether that information will change frequently.

Circulate: Allow students to complete the rest of the activity guide in their groups. As they fill out the charts, ask them to elaborate on why they thought each input should be stored or not.

Outfit Picker

The first app asks users to input their favorite color, the current season, and the weather, then outputs a picture of an outfit based on the user input.

Friend Finder

The second app asks users to input which friends should be on their friends list, then outputs a map that displays the locations of the friends on the list.

Choose a Kid's Movie

The third app asks users to input several preferences around movies, then outputs a movie recommendation based on the user's preferences.


As groups move on to the final activity, you may need to briefly explain what a guideline is and what the question is asking for. Make sure that all groups have time to come up with guidelines, even if they have to skip parts of the earlier chart.

Assessment Opportunity

Student answers may vary, but in general, they should realize that whether information should or should not be stored relates to how frequently it changes, if changes at all.

Circulate: If groups get stuck writing their guidelines, ask them about which inputs they said should be stored in the other apps. Ask them to see if they can find any similarities between which inputs were stored and were not stored. Remind them that they can also write guidelines about which inputs were not stored.

Once most of the groups are done writing their guidelines, bring the class back together and ask if any group would like to share one of their guidelines.

Introducing the IOSP Model (20 min)


Now we can understand a computer as a machine that does four things: input, output, storage, and processing

Show them the video introducing the IOSP model.

Teaching Tip

If you are using journaling, prompt the students to write their answers down in their journals

Prompt for discussion with two discussion questions.

  1. Think of something you do on the computer. What sort of input, output, storage, and processing are happening?

  2. What kinds of input, output, storage, and processing are used in a modern smartphone?

Finally, look at the poster from the "What is a Computer?" lesson and check to see if any of the machines should be reclassified as computers or not computers based on this new IOSP model.

Wrap Up (5 min)

Discussion Goal

As student share their ideas, ensure that they are using the key vocabulary of the lesson:

storage - saving information to use in the future


Prompt: Think of an app you would like to make. What information would it store?

Share: Time permitting, allow students to share out their ideas.

View on Code Studio

Outfit Picker

Input - Favorite color - Season - Weather

Output - Shirt - Pants - Items to bring (e.g. umbrella)

Processing - IF it is raining, THEN carry an umbrella. - IF it is autumn or winter, THEN wear long pants. - MATCH favorite color to shirt color.

View on Code Studio

Friend Finder

Input: - Friend list - Friend requests - Adding a friend - Removing a friend

Output: - Friend locations

Processing: - IF this person is a friend THEN find their location

View on Code Studio

Kids Movie Recommender

Input: - Favorite movie - Genre - Animated movie or not?

Output: - Movie recommendation

Processing: - IF they want an animated movie THEN choose from the animated movies ELSE choose from the live action movies - MATCH the genre they want with a movie of that genre

View on Code Studio

Discussion Goals

This discussion should allow students to review the input, output, storage, and processing model that they have been exploring in the past few lessons. While they should be familiar with how the model works with apps, there may still be questions around other computing devices, and around the examples shown later in the lesson. For example, one common source of controversy around processing is whether some devices are processing information themselves, or whether the user is processing the information, while the device simply stores information (e.g. the abacus).

View on Code Studio

Questions to think about

  • Think of something you do on the computer. What sort of input, output, storage, and processing are happening?

Standards Alignment

View full course alignment

CSTA K-12 Computer Science Standards (2017)

AP - Algorithms & Programming
  • 2-AP-10 - Use flowcharts and/or pseudocode to address complex problems as algorithms.
IC - Impacts of Computing
  • 2-IC-20 - Compare tradeoffs associated with computing technologies that affect people's everyday activities and career options.