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Binary Numbers

Eighth graders learn how computers represent everything with just two digits, 0 and 1, from numbers and text to images, and check what they know about binary.

Grade 8Binary Numbers50 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 binary.
  • ✓Read a bit and byte.
  • ✓Convert small numbers.
  • ✓See why computers use it.
Essential Question

Computers represent everything with just 0 and 1. How does binary work, and why is it the language of every computer?

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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

Binary Check

Project this and answer each question about how computers use 0s and 1s — read the explanation after each one.

🔢 Check what you know about binary numbersTry it
Answer each question about how computers use 0s and 1s.
The Lesson · Explicit teaching

50 minutes, five moves

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

1

Hook — Two Digits, Everything

5 min

Computers only really know 0 and 1. How can just two digits store numbers, words, pictures, and music?

👩‍🏫 Teacher Moves

  • Show an on/off switch.
  • Ask how two states hold data.
  • Set the goal.

🎒 Student Actions

  • Think.
  • Share.
  • Get ready.
2

Use — Binary Check

12 min

Students answer questions about binary.

👩‍🏫 Teacher Moves

  • Send students to the Binary Check.
  • Answer each question.
  • Read the why.

🎒 Student Actions

  • Answer.
  • Check.
  • Read it.
3

Modify — Count in Binary

13 min

Students convert small numbers.

👩‍🏫 Teacher Moves

  • Pick a number under 16.
  • Write it in binary.
  • Check your work.

🎒 Student Actions

  • Pick.
  • Write.
  • Check.
4

Create — Binary Message

15 min

Students encode with binary.

👩‍🏫 Teacher Moves

  • Pick a short word.
  • Encode each letter's number.
  • Share the code.

🎒 Student Actions

  • Pick.
  • Encode.
  • Share.
5

Reflect — On and Off

5 min

Students reflect on why computers use binary.

👩‍🏫 Teacher Moves

  • Why do computers use binary?
  • How many values can one bit hold?
  • Complete the exit ticket.

🎒 Student Actions

  • Say it.
  • Say it.
  • 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 in binary form.

CSTA
2-CS-01

Explain why computers use the binary system.

CSTA
2-DA-08

Convert between binary and decimal for small numbers.

ISTE
5

Understand how computers represent information.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Binary picture cards.
  • Sentence frame: “Binary uses ___ .”
  • Answer one question at a time.

Support & Access

IEP / 504
  • Start with on/off switches.
  • Count 0 to 4 in binary together.
  • Review one idea at a time.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Convert larger numbers both ways.
  • Encode a word in ASCII binary.
  • Explore how images use bits.
Materials

What to gather

  • 📽️Projector / board
  • 🔢Binary cards / chips
  • 💻Binary Check
  • 🔀Place-value charts
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

binarya number system using only 0 and 1bita single binary digit, 0 or 1byteeight bits, enough for one characterdecimalthe base-10 number system people usebasehow many digits a number system usesencodeto turn information into a code like binaryASCIIa code that maps characters to numbersplace valuethe value a digit has based on its position
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 two digits does binary use?
Only 0 and 1, which map onto a switch being off or on.
QUESTION 2
Why do computers use binary?
Because hardware can easily and reliably represent two states (off and on), which match 0 and 1.
QUESTION 3
How many bits are in a byte?
Eight bits make one byte, enough to represent one character of text.

Create: a binary message.

Have students pick a short word, encode each letter's number into binary, and share the code for a partner to decode, so binary connects to real information. A printable binary 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.

🃏 Binary NumbersFlip
Card 1
Term
Tap to flip →
Meaning
0

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Practice · Quiz

Check your understanding

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

📝 Binary NumbersQuiz
Score: 0
1 / 6
Question 1
0%

Nice work!

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.

🖨️ Binary NumbersPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: ASCII, base, binary, bit, byte, decimal, encode, place value
  1. the base-10 number system people use
  2. how many digits a number system uses
  3. a code that maps characters to numbers
  4. the value a digit has based on its position
  5. eight bits, enough for one character
  6. to turn information into a code like binary
  7. a number system using only 0 and 1
  8. a single binary digit, 0 or 1

Part B · Show what you learned

  1. What two digits does binary use?
  2. Why do computers use binary?
  3. How many bits are in a byte?
Answer key — Part A: 1) decimal · 2) base · 3) ASCII · 4) place value · 5) byte · 6) encode · 7) binary · 8) bit
Part B: 1) Only 0 and 1, which map onto a switch being off or on. 2) Because hardware can easily and reliably represent two states (off and on), which match 0 and 1. 3) Eight bits make one byte, enough to represent one character of text.