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Arrays & Lists

Tenth graders learn about arrays and lists — ordered collections that store many values in a single variable — and how indexes let programs access, change, and loop through data efficiently.

Grade 10Data Structures50 minutes1 class periodUse → Modify → CreateExplicit teaching4 StandardsCSTA
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Define an array.
  • ✓Use an index.
  • ✓Access and change elements.
  • ✓Loop through a list.
Essential Question

What if a program needs to store 100 test scores? Making 100 variables would be a nightmare. Arrays solve this. How do arrays store and organize many values at once?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Explore · Interactive

Arrays Check

Project each item and have students answer about arrays. The tool explains collections, indexes, and elements.

📦 Understand arrays & listsTry it
Answer each question about arrays and lists.
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 — 100 Scores

5 min

Storing 100 scores in 100 variables is a nightmare — what’s the fix?

👩‍🏫 Teacher Moves

  • Pose the problem.
  • Introduce arrays.
  • Set the goal.

🎒 Student Actions

  • Consider.
  • Meet arrays.
  • Predict.
2

Unplugged — Unplug It

11 min

Students practice.

👩‍🏫 Teacher Moves

  • Number a row of boxes.
  • Store values by index.
  • Access one by index.

🎒 Student Actions

  • Number them.
  • Store values.
  • Access it.
3

Use — Arrays in Code

14 min

Students use.

👩‍🏫 Teacher Moves

  • Send students to Arrays Check.
  • Note indexes.
  • Access elements.

🎒 Student Actions

  • Answer.
  • Note index.
  • Access.
4

Modify — Modify It

14 min

Students modify.

👩‍🏫 Teacher Moves

  • Change an element.
  • Add or remove an item.
  • Loop through a list.

🎒 Student Actions

  • Change it.
  • Add/remove.
  • Loop it.
5

Create — Create

6 min

Students conclude.

👩‍🏫 Teacher Moves

  • Create and fill a list.
  • Access an element.
  • Complete the exit ticket.

🎒 Student Actions

  • Create it.
  • Access it.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

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

CSTA
3A-AP-14

Use lists to simplify solutions.

CSTA
3A-DA-09

Translate between data representations.

CSTA
3A-AP-13

Create programs that use collections.

ISTE
5

Computational Thinker.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Array + index diagrams.
  • Sentence frame: “arr[__] is ___.”
  • Use numbered boxes.

Support & Access

IEP / 504
  • Start with a 3-item list.
  • Use physical boxes.
  • Access index 0.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Loop through and total a list.
  • Use 2-D arrays.
  • Sort a list.
Materials

What to gather

  • 📽️Projector / board
  • 📦Numbered boxes
  • 💻Arrays Check
  • 💻Coding tool
  • ✏️Pens
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

arrayan ordered collection of valueslistanother name for an arrayindexthe position number of an elementelementone item in an arrayzero-indexedcounting positions from 0lengthhow many elements an array hascollectiona group of valuesiterateto loop through elements
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 array?
An ordered collection that stores many values in one variable.
QUESTION 2
What index is the first element of an array in most languages?
0.
QUESTION 3
If names = [“Ava”, “Ben”, “Cy”], what is names[2]?
“Cy” — index 2 is the third element.

Create: build a list.

Have students create a list of five items and write how they would access the first and last elements. A printable arrays sheet 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.

🃏 Arrays & ListsFlip
Card 1
Term
Tap to flip →
Meaning
0

Nice work!

Practice · Quiz

Check your understanding

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

📝 Arrays & ListsQuiz
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.

🖨️ Arrays & ListsPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: array, collection, element, index, iterate, length, list, zero-indexed
  1. one item in an array
  2. to loop through elements
  3. the position number of an element
  4. how many elements an array has
  5. counting positions from 0
  6. an ordered collection of values
  7. another name for an array
  8. a group of values

Part B · Show what you learned

  1. What is an array?
  2. What index is the first element of an array in most languages?
  3. If names = [“Ava”, “Ben”, “Cy”], what is names[2]?
Answer key — Part A: 1) element · 2) iterate · 3) index · 4) length · 5) zero-indexed · 6) array · 7) list · 8) collection
Part B: 1) An ordered collection that stores many values in one variable. 2) 0. 3) “Cy” — index 2 is the third element.