Home›Lesson Plans›Computer Science›Computational Thinking · Grades 3–5

What Is an Algorithm? A Recipe of Exact Steps

Students discover that an algorithm is just a clear set of step-by-step instructions — and that computers, like very literal helpers, do exactly what the steps say, in order.

Grades 3–5Algorithms45 minutes1 class periodCode LessonExplicit teaching4 StandardsISTE + CSTA
Start the Lesson
Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Explain that an algorithm is a set of step-by-step instructions.
  • ✓Put the steps of a task in the correct order.
  • ✓Explain why order matters in instructions.
  • ✓Write a clear algorithm for a simple task.
Essential Question

A computer will do exactly what you tell it — no more, no less. So how do you write instructions clear enough that even a robot can follow them?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Order the Steps · Interactive

Order the Steps

Project this and have students put the steps of making a jam sandwich in the right order. The tool checks whether the algorithm works.

🧾 Put the steps in order — make an algorithmTry it
The Lesson · Use · Modify · Create

45 minutes, five moves

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

1

Warm-Up — The Literal Robot

5 min

Give a robot silly, unclear directions — what happens?

👩‍🏫 Teacher Moves

  • Pretend to be a robot; take students’ vague steps literally.
  • Show how unclear steps fail.
  • Set the goal: clear algorithms.

🎒 Student Actions

  • Give the “robot” directions.
  • Laugh at the literal results.
  • Predict what “algorithm” means.
2

Learn — Steps in Order

10 min

Teacher defines algorithm.

👩‍🏫 Teacher Moves

  • Define algorithm = step-by-step instructions.
  • Show that order matters.
  • Model ordering a real task.

🎒 Student Actions

  • Learn the definition.
  • See why order matters.
  • Order a simple task.
3

Use It — Order the Steps

12 min

Students use the tool.

👩‍🏫 Teacher Moves

  • Have students order the sandwich steps.
  • Check if the algorithm “works.”
  • Fix any out-of-order steps.

🎒 Student Actions

  • Order the steps.
  • Run/check the algorithm.
  • Fix the order if needed.
4

Create — Write Your Own

13 min

Students create an algorithm.

👩‍🏫 Teacher Moves

  • Assign a task (brush teeth, tie shoes).
  • Have students write clear numbered steps.
  • Trade and “run” each other’s.

🎒 Student Actions

  • Write a clear algorithm.
  • Number the steps.
  • Test a partner’s.
5

Share — Share

5 min

Students share an algorithm.

👩‍🏫 Teacher Moves

  • Invite students to read an algorithm aloud.
  • Have the class “run” it literally.
  • Hand out the exit ticket.

🎒 Student Actions

  • Read an algorithm.
  • Fix a missing step.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

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

CSTA
1A-AP-10

Develop programs with sequences and simple loops to express ideas or address a problem.

CSTA
1B-AP-08

Compare and refine multiple algorithms for the same task and determine which is most appropriate.

ISTE
Computational Thinker

Break problems into parts and create step-by-step algorithms.

CCSS
RI.3.3

Describe the steps in a technical procedure using language that pertains to sequence.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Picture cards of steps to order.
  • Sentence frame: “First ___. Next ___.”
  • Act out each step in order.

Support & Access

IEP / 504
  • Order three steps before four.
  • Provide the first step to start.
  • Use picture-supported steps.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Write an algorithm with a repeated step.
  • Find a missing step in a broken algorithm.
  • Compare two algorithms for the same task.
Materials

What to gather

  • 📽️Projector / board
  • 📓Notebooks
  • 💻Order the Steps
  • 🗂️Step cards
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

algorithma set of step-by-step instructionsstepone instruction in an algorithmsequencethe order of stepsinstructiona command to followorderthe arrangement of stepsinputwhat you start withoutputthe resultdebugto find and fix a mistake
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 an algorithm?
A set of clear, step-by-step instructions for doing a task.
QUESTION 2
Why does the order of steps matter in an algorithm?
A computer follows steps exactly in order — if they’re out of order, you get the wrong result (like cutting the sandwich before making it).
QUESTION 3
Write the first two steps of an algorithm for washing your hands.
Sample: 1) Turn on the water. 2) Wet your hands and add soap.

Going deeper? Program a partner.

Have one student write an algorithm to draw a simple shape, then a partner follows it exactly — and they debug any unclear steps together. A printable “program a partner” sheet is in the CS 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.

🃏 What Is an Algorithm?Flip
Card 1
Term
Tap to flip →
Meaning
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Practice · Quiz

Check your understanding

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

📝 What Is an Algorithm?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.

🖨️ What Is an Algorithm?Print
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: algorithm, debug, input, instruction, order, output, sequence, step
  1. a set of step-by-step instructions
  2. the arrangement of steps
  3. a command to follow
  4. to find and fix a mistake
  5. the result
  6. one instruction in an algorithm
  7. the order of steps
  8. what you start with

Part B · Show what you learned

  1. What is an algorithm?
  2. Why does the order of steps matter in an algorithm?
  3. Write the first two steps of an algorithm for washing your hands.
Answer key — Part A: 1) algorithm · 2) order · 3) instruction · 4) debug · 5) output · 6) step · 7) sequence · 8) input
Part B: 1) A set of clear, step-by-step instructions for doing a task. 2) A computer follows steps exactly in order — if they’re out of order, you get the wrong result (like cutting the sandwich before making it). 3) Sample: 1) Turn on the water. 2) Wet your hands and add soap.