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How Computers Store Images

Seventh graders discover that every digital image is a grid of tiny colored squares — pixels — and each pixel’s color is stored as amounts of red, green, and blue (RGB). More pixels means more detail. They test the idea, then build a pixel picture.

Grade 7How Computers Store Images50 minutes1 class periodCSTA / ISTEExplicit teaching4 StandardsCSTA
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Explain a pixel.
  • ✓Describe color with RGB.
  • ✓Connect pixels to resolution.
  • ✓Make a pixel image.
Essential Question

How does a computer store a picture as numbers?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Check It · Interactive

How Images Are Stored

Project each item and have students answer about pixels and color.

🖼️ Understand how computers store imagesTry it
Answer each question about pixels and images.
The Lesson · Use → Modify → Create (a coding progression with Unplugged practice)

50 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Hook — Zoom In

6 min

What do you see if you zoom WAY into a photo?

👩‍🏫 Teacher Moves

  • Zoom into an image.
  • Ask what the squares are.
  • Set the goal.

🎒 Student Actions

  • Look.
  • Guess.
  • Get ready.
2

Use — Pixels & RGB

12 min

Students use the idea.

👩‍🏫 Teacher Moves

  • Send students to How Images Are Stored.
  • Note pixels & RGB.
  • Note pixels & resolution.

🎒 Student Actions

  • Answer.
  • Note it.
  • Note it.
3

Modify — Change the Color

13 min

Students modify.

👩‍🏫 Teacher Moves

  • Mix RGB values to make a color.
  • Change a few pixels.
  • See the picture change.

🎒 Student Actions

  • Mix.
  • Change.
  • See it.
4

Create — Make a Pixel Image

13 min

Students create.

👩‍🏫 Teacher Moves

  • Color a small pixel grid.
  • Choose RGB for each cell.
  • Name your picture.

🎒 Student Actions

  • Color.
  • Choose.
  • Name.
5

Reflect — Reflect

6 min

Students close.

👩‍🏫 Teacher Moves

  • Say what a pixel is.
  • Say what RGB stands for.
  • Complete the exit ticket.

🎒 Student Actions

  • Say it.
  • Say.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

Aligned to the CSTA K-12 Computer Science Standards and the ISTE Standards for Students.

CSTA
2-DA-07

Represent data using multiple encoding schemes.

CSTA
2-DA-08

Collect data and create visualizations.

CSTA
2-CS-01

Recommend hardware/software for displaying media.

ISTE
5 Computational Thinker

Represent data to solve problems.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Use a grid & crayons.
  • Frame: “pixel = tiny colored square.”
  • Mix RGB with light.

Support & Access

IEP / 504
  • Color a 4x4 grid.
  • Use 3 colors.
  • Label R, G, B.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Compute a file’s pixel count.
  • Compare low vs high resolution.
  • Encode a pixel in binary.
Materials

What to gather

  • 📽️Screen / board
  • 🖼️Pixel grid paper
  • 💻How Images Are Stored
  • 🖍️RGB color chart
  • 📓Notebooks
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

pixelone tiny colored square in an imageRGBred, green, blue — how color is storedresolutionhow many pixels an image hasgridthe rows and columns of pixelscolor valuethe number for each color amountimage filestored pixel datazoomenlarge to see individual pixelsencodeto store something as numbers
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
What is a digital image made of?
Tiny colored squares called pixels.
QUESTION 2
What does RGB stand for?
Red, Green, Blue.
QUESTION 3
What does more pixels give an image?
Higher resolution and more detail.

Reflect: how computers store images.

Have students design a small pixel picture on a grid. A printable pixel-image worksheet is in the Computer Science library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 CS How Computers Store Images (Grade 7)Flip
Card 1
Term
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Meaning
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Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 CS How Computers Store Images (Grade 7)Quiz
Score: 0
1 / 6
Question 1
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Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ CS How Computers Store Images (Grade 7)Print
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: color value, encode, grid, image file, pixel, resolution, RGB, zoom
  1. the rows and columns of pixels
  2. enlarge to see individual pixels
  3. one tiny colored square in an image
  4. red, green, blue — how color is stored
  5. the number for each color amount
  6. to store something as numbers
  7. stored pixel data
  8. how many pixels an image has

Part B · Show what you learned

  1. What is a digital image made of?
  2. What does RGB stand for?
  3. What does more pixels give an image?
Answer key — Part A: 1) grid · 2) zoom · 3) pixel · 4) RGB · 5) color value · 6) encode · 7) image file · 8) resolution
Part B: 1) Tiny colored squares called pixels. 2) Red, Green, Blue. 3) Higher resolution and more detail.