Please enable JavaScript to use CodeHS

DE 3A: 3A-AP-14

  1. Frameworks
  2. Delaware 3A

CodeHS Lessons

Use lists to simplify solutions, generalizing computational problems instead of repeatedly using simple variables.

Introduction to Computer Science in JavaScript (Corgi)
Standard
22.1 Intro to Sets
22.2 Intro to Grids
22.3 Looping Over a Grid
22.4 Grid Example: Get a Row
27.1 Game Design: Helicopter
20.1 Intro to Arrays
20.2 Adding & Removing from an Array
20.3 Iterating Through an Array
21.1 Intro to Objects
21.4 Iterating Through an Object

Introduction to Python Programming
Standard
12.1 Tuples
12.1 Tuples
12.2 Lists
12.2 Lists
12.3 For Loops and Lists
12.3 For Loops and Lists
12.4 List Methods
12.4 List Methods
13.1 2d Lists
13.2 List Comprehensions
13.3 Packing and Unpacking
13.4 Dictionaries
22.5 Class Variables vs. Instance Variables
20.1 Project: Who Said It?
22.1 Classes and Objects
22.1 Classes and Objects
22.5 Class Variables vs. Instance Variables
20.1 Project: Who Said It?

AP Computer Science A (Nitro)
Standard
6.1 Array
6.2 Traversing Arrays
7.1 ArrayList
7.2 ArrayList Methods
7.3 Traversing ArrayLists

AP Computer Science Principles in JavaScript
Standard
7.1 Intro to Lists/Arrays
7.2 Indexing Into an Array
7.5 Iterating Over an Array
7.6 Finding an Element in a List

AP Computer Science Principles in Python
Standard
7.1 Tuples
7.2 Lists
7.3 For Loops and Lists
7.4 List Methods
34.3 Packing and Unpacking
29.1 Project: Who Said It?
27.5 Class Variables vs. Instance Variables
27.1 Classes and Objects
34.5 Equivalence vs. Identity
34.4 Dictionaries
34.1 2d Lists
34.2 List Comprehensions
34.1 2d Lists
29.1 Project: Who Said It?
27.5 Class Variables vs. Instance Variables
27.1 Classes and Objects
34.5 Equivalence vs. Identity
34.4 Dictionaries
34.3 Packing and Unpacking
34.2 List Comprehensions

Web Development
Standard
1.9 Keyboard Interactions
2.2 Iterating with jQuery
4.2 Storing Data with Local Storage
4.3 Storing Data Structures with Local Storage
4.7 Storing Data with Firebase
4.10 For/In Loops
9.19 Intro to Lists/Arrays
9.20 Indexing Into an Array
9.21 Adding/Removing From an Array
9.22 Array Length and Looping Through Arrays
9.19 Intro to Lists/Arrays
9.20 Indexing Into an Array
9.21 Adding/Removing From an Array
9.22 Array Length and Looping Through Arrays

Web Design and Development
Standard
5.8 Keyboard Interactions
6.2 Iterating with jQuery
8.2 Storing Data with Local Storage
8.3 Storing Data Structures with Local Storage
8.7 Storing Data with Firebase
8.10 For/In Loops

Fundamentals of Cybersecurity
Standard
13.5 Arrays and Objects
13.5 Arrays and Objects

AP Computer Science Principles: Cybersecurity
Standard
7.1 Intro to Lists/Arrays
7.2 Indexing Into an Array
7.5 Iterating Over an Array
7.6 Finding an Element in a List

Video Game Design in JavaScript
Standard
13.1 Intro to Arrays
13.2 Adding & Removing from an Array
13.3 Iterating Through an Array
14.1 Intro to Objects
14.4 Iterating Through an Object
16.1 Game Design: Helicopter
22.1 Intro to Sets
22.2 Intro to Grids
22.3 Looping Over a Grid
22.4 Grid Example: Get a Row

Introduction to Computer Science in JavaScript (Bulldog)
Standard
13.1 Intro to Arrays
13.2 Adding & Removing from an Array
13.3 Iterating Through an Array
14.1 Intro to Objects
14.4 Iterating Through an Object
16.1 Game Design: Helicopter
20.1 Intro to Sets
20.2 Intro to Grids
20.3 Looping Over a Grid
20.4 Grid Example: Get a Row

Introduction to Computer Science in JavaScript (Collie)
Standard
22.1 Intro to Sets
22.2 Intro to Grids
22.3 Looping Over a Grid
22.4 Grid Example: Get a Row
25.1 Game Design: Helicopter
20.1 Intro to Arrays
20.2 Adding & Removing from an Array
20.3 Iterating Through an Array
21.1 Intro to Objects
21.4 Iterating Through an Object

Mobile Apps
Standard
10.1 Using Arrays and Indexing to Set State
10.1 Using Arrays and Indexing to Set State
10.2 Mapping Through Objects in Arrays
10.2 Mapping Through Objects in Arrays

AP Computer Science A Labs
Standard
7.1 Writing BlackJack
7.1 Writing BlackJack

Intro to Programming in Python with Arduino
Standard
9.1 Tuples
9.1 Tuples
9.2 Lists
9.2 Lists
9.3 For Loops and Lists
9.3 For Loops and Lists
9.4 List Methods
9.4 List Methods
10.1 2d Lists
10.1 2d Lists
10.2 List Comprehensions
10.2 List Comprehensions
10.3 Packing and Unpacking
10.3 Packing and Unpacking
10.4 Dictionaries
10.4 Dictionaries
10.5 Equivalence vs. Identity
10.5 Equivalence vs. Identity
14.5 Class Variables vs. Instance Variables
14.1 Classes and Objects
14.1 Classes and Objects
14.5 Class Variables vs. Instance Variables

Intro to Programming in JavaScript with Arduino
Standard
22.1 Game Design: Helicopter
22.1 Game Design: Helicopter

Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

AP Computer Science A (Mocha)
Standard
5.2 Introduction to Arrays
5.2 Introduction to Arrays
5.3 Using Arrays
5.3 Using Arrays
5.5 ArrayList Methods
5.5 ArrayList Methods
5.6 Arrays vs ArrayLists
5.6 Arrays vs ArrayLists
5.8 The List Interface
5.8 The List Interface
5.9 2D Arrays (Matrices or Grids)
5.9 2D Arrays (Matrices or Grids)
5.11 HashMaps
5.11 HashMaps
5.12 Binary
5.12 Binary
6.1 Writing BlackJack
6.1 Writing BlackJack
10.1 Final Project
10.1 Final Project

Introduction to Computer Science in JavaScript (Golden) (2022)
Standard
25.10 Iterating Over an Object
25.2 Indexing Into an Array
25.3 Adding/Removing From an Array
25.4 Array Length and Looping Through Arrays
25.5 Iterating Over an Array
25.6 Finding an Element in a List
25.7 Removing an Element From an Array
25.8 Intro to Objects/Maps
25.9 Basics of Objects
25.1 Intro to Lists/Arrays
25.11 When Do I Use an Object?
25.12 Intro to Sets
25.13 Intro to Grids
25.14 Looping Over a Grid
25.15 Grid Example: Get a Row
25.16 Data Structures Challenges
27.1 Game Design: Helicopter
21.1 Evolution Simulation
25.10 Iterating Over an Object
25.2 Indexing Into an Array
25.3 Adding/Removing From an Array
25.4 Array Length and Looping Through Arrays
25.5 Iterating Over an Array
25.6 Finding an Element in a List
25.7 Removing an Element From an Array
25.8 Intro to Objects/Maps
25.9 Basics of Objects
25.1 Intro to Lists/Arrays
25.11 When Do I Use an Object?
25.12 Intro to Sets
25.13 Intro to Grids
25.14 Looping Over a Grid
25.15 Grid Example: Get a Row
25.16 Data Structures Challenges
27.1 Game Design: Helicopter
21.1 Evolution Simulation

Introduction to Computer Science in JavaScript (Bulldog) (2022)
Standard
12.1 Intro to Lists/Arrays
12.1 Intro to Lists/Arrays
12.2 Indexing Into an Array
12.2 Indexing Into an Array
12.3 Adding/Removing From an Array
12.3 Adding/Removing From an Array
12.4 Array Length and Looping Through Arrays
12.4 Array Length and Looping Through Arrays
12.5 Iterating Over an Array
12.5 Iterating Over an Array
12.6 Finding an Element in a List
12.6 Finding an Element in a List
12.7 Removing an Element From an Array
12.7 Removing an Element From an Array
12.8 Intro to Objects/Maps
12.8 Intro to Objects/Maps
12.9 Basics of Objects
12.9 Basics of Objects
12.10 Iterating Over an Object
12.10 Iterating Over an Object
12.11 When Do I Use an Object?
12.11 When Do I Use an Object?
12.12 Intro to Sets
12.12 Intro to Sets
12.13 Intro to Grids
12.13 Intro to Grids
12.14 Looping Over a Grid
12.14 Looping Over a Grid
12.15 Grid Example: Get a Row
12.15 Grid Example: Get a Row
12.16 Data Structures Challenges
12.16 Data Structures Challenges
14.1 Game Design: Helicopter
14.1 Game Design: Helicopter
24.1 Evolution Simulation
24.1 Evolution Simulation

Introduction to Computer Science (Collie) (2022)
Standard
21.10 Iterating Over an Object
21.2 Indexing Into an Array
21.3 Adding/Removing From an Array
21.4 Array Length and Looping Through Arrays
21.5 Iterating Over an Array
21.6 Finding an Element in a List
21.7 Removing an Element From an Array
21.8 Intro to Objects/Maps
21.9 Basics of Objects
21.1 Intro to Lists/Arrays
21.11 When Do I Use an Object?
21.12 Intro to Sets
21.13 Intro to Grids
21.14 Looping Over a Grid
21.15 Grid Example: Get a Row
21.16 Data Structures Challenges
23.1 Game Design: Helicopter
16.1 Evolution Simulation
21.10 Iterating Over an Object
21.2 Indexing Into an Array
21.3 Adding/Removing From an Array
21.4 Array Length and Looping Through Arrays
21.5 Iterating Over an Array
21.6 Finding an Element in a List
21.7 Removing an Element From an Array
21.8 Intro to Objects/Maps
21.9 Basics of Objects
21.1 Intro to Lists/Arrays
21.11 When Do I Use an Object?
21.12 Intro to Sets
21.13 Intro to Grids
21.14 Looping Over a Grid
21.15 Grid Example: Get a Row
21.16 Data Structures Challenges
23.1 Game Design: Helicopter
16.1 Evolution Simulation

Intro to Computer Science in Python 3
Standard
8.1 Tuples
8.1 Tuples
8.2 Lists
8.2 Lists
8.3 For Loops and Lists
8.3 For Loops and Lists
8.4 List Methods
8.4 List Methods
9.1 2d Lists
9.1 2d Lists
9.2 List Comprehensions
9.2 List Comprehensions
9.3 Packing and Unpacking
9.3 Packing and Unpacking
9.4 Dictionaries
9.4 Dictionaries
9.5 Equivalence vs. Identity
9.5 Equivalence vs. Identity
16.1 Project: Who Said It?
12.5 Class Variables vs. Instance Variables
12.1 Classes and Objects
12.1 Classes and Objects
12.5 Class Variables vs. Instance Variables
16.1 Project: Who Said It?

Arizona Software and App Design I
Standard
6.13 Intro to Lists/Arrays
6.14 Indexing Into an Array
6.15 Adding/Removing From an Array
6.16 Array Length and Looping Through Arrays
7.8 Keyboard Interactions
8.2 Iterating with jQuery
10.2 Storing Data with Local Storage
10.3 Storing Data Structures with Local Storage
10.7 Storing Data with Firebase
10.10 For/In Loops

Arizona Software and App Design II
Standard
8.2 Introduction to Arrays
8.3 Using Arrays
8.5 ArrayList Methods
8.6 Arrays vs ArrayLists
8.8 The List Interface
8.9 2D Arrays
8.11 HashMaps
8.12 Binary

Arizona Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Arkansas Programming I (JavaScript)
Standard
10.12 Intro to Lists/Arrays
10.12 Intro to Lists/Arrays
10.13 Adding/Removing From an Array
10.13 Adding/Removing From an Array
10.14 Array Length and Looping Through Arrays
10.14 Array Length and Looping Through Arrays
10.15 Iterating Over an Array
10.15 Iterating Over an Array
14.8 Grid Example: Get a Row
14.7 Looping Over a Grid
14.6 Intro to Grids
14.5 Intro to Sets
14.4 When Do I Use an Object?
14.3 Iterating Over an Object
14.2 Basics of Objects
14.1 Intro to Objects/Maps
13.3 Removing an Element From an Array
13.2 Finding an Element in a List
14.9 Data Structures Challenges
13.1 Indexing Into an Array
14.9 Data Structures Challenges
14.8 Grid Example: Get a Row
14.7 Looping Over a Grid
14.6 Intro to Grids
14.5 Intro to Sets
14.4 When Do I Use an Object?
14.3 Iterating Over an Object
14.2 Basics of Objects
14.1 Intro to Objects/Maps
13.3 Removing an Element From an Array
13.2 Finding an Element in a List
13.1 Indexing Into an Array

Arkansas Programming I (Python)
Standard
10.1 Tuples
10.1 Tuples
10.2 Lists
10.2 Lists
10.3 For Loops and Lists
10.3 For Loops and Lists
10.4 List Methods
10.4 List Methods
11.1 2d Lists
11.1 2d Lists
11.2 List Comprehensions
11.2 List Comprehensions
11.3 Packing and Unpacking
11.3 Packing and Unpacking
11.4 Dictionaries
11.4 Dictionaries
11.5 Equivalence vs. Identity
11.5 Equivalence vs. Identity
18.1 Project: Who Said It?
18.1 Project: Who Said It?

California Computer Science
Standard
10.11 Intro to Lists/Arrays
10.11 Intro to Lists/Arrays
10.12 Adding/Removing From an Array
10.12 Adding/Removing From an Array
10.13 Array Length and Looping Through Arrays
10.13 Array Length and Looping Through Arrays
10.14 Iterating Over an Array
10.14 Iterating Over an Array
18.8 Grid Example: Get a Row
18.7 Looping Over a Grid
18.6 Intro to Grids
18.5 Intro to Sets
18.4 When Do I Use an Object?
18.3 Iterating Over an Object
18.2 Basics of Objects
18.1 Intro to Objects/Maps
17.3 Removing an Element From an Array
17.2 Finding an Element in a List
18.9 Data Structures Challenges
17.1 Indexing Into an Array
18.9 Data Structures Challenges
18.8 Grid Example: Get a Row
18.7 Looping Over a Grid
18.6 Intro to Grids
18.5 Intro to Sets
18.4 When Do I Use an Object?
18.3 Iterating Over an Object
18.2 Basics of Objects
18.1 Intro to Objects/Maps
17.3 Removing an Element From an Array
17.2 Finding an Element in a List
17.1 Indexing Into an Array

Delaware Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Florida Computing Ideas
Standard
11.11 Intro to Lists/Arrays
11.11 Intro to Lists/Arrays
11.12 Adding/Removing From an Array
11.12 Adding/Removing From an Array
11.13 Array Length and Looping Through Arrays
11.13 Array Length and Looping Through Arrays
11.14 Iterating Over an Array
11.14 Iterating Over an Array
19.8 Grid Example: Get a Row
19.7 Looping Over a Grid
19.6 Intro to Grids
19.5 Intro to Sets
19.4 When Do I Use an Object?
19.3 Iterating Over an Object
19.2 Basics of Objects
19.1 Intro to Objects/Maps
18.3 Removing an Element From an Array
18.2 Finding an Element in a List
19.9 Data Structures Challenges
18.1 Indexing Into an Array
19.9 Data Structures Challenges
19.8 Grid Example: Get a Row
19.7 Looping Over a Grid
19.6 Intro to Grids
19.5 Intro to Sets
19.4 When Do I Use an Object?
19.3 Iterating Over an Object
19.2 Basics of Objects
19.1 Intro to Objects/Maps
18.3 Removing an Element From an Array
18.2 Finding an Element in a List
18.1 Indexing Into an Array

Georgia Computer Science Principles
Standard
7.1 Intro to Lists/Arrays
7.2 Indexing Into an Array
7.5 Iterating Over an Array
7.6 Finding an Element in a List

Georgia Introduction to Digital Technology
Standard
17.11 Intro to Lists/Arrays
20.9 Data Structures Challenges
20.8 Grid Example: Get a Row
20.7 Looping Over a Grid
20.6 Intro to Grids
20.5 Intro to Sets
20.4 When Do I Use an Object?
20.3 Iterating Over an Object
20.2 Basics of Objects
20.1 Intro to Objects/Maps
19.3 Removing an Element From an Array
19.2 Finding an Element in a List
17.14 Iterating Over an Array
17.13 Array Length and Looping Through Arrays
17.12 Adding/Removing From an Array
19.1 Indexing Into an Array
17.11 Intro to Lists/Arrays
20.9 Data Structures Challenges
20.8 Grid Example: Get a Row
20.7 Looping Over a Grid
20.6 Intro to Grids
20.5 Intro to Sets
20.4 When Do I Use an Object?
20.3 Iterating Over an Object
20.2 Basics of Objects
20.1 Intro to Objects/Maps
19.3 Removing an Element From an Array
19.2 Finding an Element in a List
17.14 Iterating Over an Array
17.13 Array Length and Looping Through Arrays
17.12 Adding/Removing From an Array
19.1 Indexing Into an Array

Georgia Foundations of Artificial Intelligence
Standard
9.1 Tuples
9.1 Tuples
9.2 Lists
9.2 Lists
9.3 For Loops and Lists
9.3 For Loops and Lists
9.4 List Methods
9.4 List Methods
9.5 2d Lists
9.5 2d Lists
17.1 Project: Who Said It?
15.5 Class Variables vs. Instance Variables
15.1 Classes and Objects
12.4 Equivalence vs. Identity
12.3 Dictionaries
12.2 Packing and Unpacking
12.1 List Comprehensions
17.1 Project: Who Said It?
15.5 Class Variables vs. Instance Variables
15.1 Classes and Objects
12.4 Equivalence vs. Identity
12.3 Dictionaries
12.2 Packing and Unpacking
12.1 List Comprehensions

Georgia Web Development
Standard
5.8 Keyboard Interactions
6.2 Iterating with jQuery
8.2 Storing Data with Local Storage
8.3 Storing Data Structures with Local Storage
8.7 Storing Data with Firebase
8.10 For/In Loops

Hawaii EXS1300 Intro to Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Illinois Introduction to Computer Science
Standard
29.9 Basics of Objects
32.1 Game Design: Helicopter
29.16 Data Structures Quiz
29.15 Grid Example: Get a Row
29.14 Looping Over a Grid
29.13 Intro to Grids
29.12 Intro to Sets
29.11 When Do I Use an Object?
29.10 Iterating Over an Object
29.1 Intro to Lists/Arrays
29.8 Intro to Objects/Maps
29.7 Removing an Element From an Array
29.6 Finding an Element in a List
29.5 Iterating Over an Array
29.4 Array Length and Looping Through Arrays
29.3 Adding/Removing From an Array
29.2 Indexing Into an Array

Indiana Introduction to Computer Science
Standard
33.10 Iterating Over an Object
33.2 Indexing Into an Array
33.3 Adding/Removing From an Array
33.4 Array Length and Looping Through Arrays
33.5 Iterating Over an Array
33.6 Finding an Element in a List
33.7 Removing an Element From an Array
33.8 Intro to Objects/Maps
33.9 Basics of Objects
33.1 Intro to Lists/Arrays
33.11 When Do I Use an Object?
33.12 Intro to Sets
33.13 Intro to Grids
33.14 Looping Over a Grid
33.15 Grid Example: Get a Row
33.16 Data Structures Challenges
35.1 Game Design: Helicopter
29.1 Evolution Simulation
33.10 Iterating Over an Object
33.2 Indexing Into an Array
33.3 Adding/Removing From an Array
33.4 Array Length and Looping Through Arrays
33.5 Iterating Over an Array
33.6 Finding an Element in a List
33.7 Removing an Element From an Array
33.8 Intro to Objects/Maps
33.9 Basics of Objects
33.1 Intro to Lists/Arrays
33.11 When Do I Use an Object?
33.12 Intro to Sets
33.13 Intro to Grids
33.14 Looping Over a Grid
33.15 Grid Example: Get a Row
33.16 Data Structures Challenges
35.1 Game Design: Helicopter
29.1 Evolution Simulation

Indiana Principles of Computing
Standard
33.10 Iterating Over an Object
33.2 Indexing Into an Array
33.3 Adding/Removing From an Array
33.4 Array Length and Looping Through Arrays
33.5 Iterating Over an Array
33.6 Finding an Element in a List
33.7 Removing an Element From an Array
33.8 Intro to Objects/Maps
33.9 Basics of Objects
33.1 Intro to Lists/Arrays
33.11 When Do I Use an Object?
33.12 Intro to Sets
33.13 Intro to Grids
33.14 Looping Over a Grid
33.15 Grid Example: Get a Row
33.16 Data Structures Challenges
35.1 Game Design: Helicopter
29.1 Evolution Simulation
33.10 Iterating Over an Object
33.2 Indexing Into an Array
33.3 Adding/Removing From an Array
33.4 Array Length and Looping Through Arrays
33.5 Iterating Over an Array
33.6 Finding an Element in a List
33.7 Removing an Element From an Array
33.8 Intro to Objects/Maps
33.9 Basics of Objects
33.1 Intro to Lists/Arrays
33.11 When Do I Use an Object?
33.12 Intro to Sets
33.13 Intro to Grids
33.14 Looping Over a Grid
33.15 Grid Example: Get a Row
33.16 Data Structures Challenges
35.1 Game Design: Helicopter
29.1 Evolution Simulation

Indiana Topics in Computer Science
Standard
6.1 Tuples
6.1 Tuples
6.2 Lists
6.2 Lists
6.3 For Loops and Lists
6.3 For Loops and Lists
6.4 List Methods
6.4 List Methods
6.5 2d Lists
6.6 Dictionaries

Indiana Computer Science I
Standard
26.10 Iterating Over an Object
26.2 Indexing Into an Array
26.3 Adding/Removing From an Array
26.4 Array Length and Looping Through Arrays
26.5 Iterating Over an Array
26.6 Finding an Element in a List
26.7 Removing an Element From an Array
26.8 Intro to Objects/Maps
26.9 Basics of Objects
26.1 Intro to Lists/Arrays
26.11 When Do I Use an Object?
26.12 Intro to Sets
26.13 Intro to Grids
26.14 Looping Over a Grid
26.15 Grid Example: Get a Row
26.16 Data Structures Challenges
28.1 Game Design: Helicopter
22.1 Evolution Simulation
26.10 Iterating Over an Object
26.2 Indexing Into an Array
26.3 Adding/Removing From an Array
26.4 Array Length and Looping Through Arrays
26.5 Iterating Over an Array
26.6 Finding an Element in a List
26.7 Removing an Element From an Array
26.8 Intro to Objects/Maps
26.9 Basics of Objects
26.1 Intro to Lists/Arrays
26.11 When Do I Use an Object?
26.12 Intro to Sets
26.13 Intro to Grids
26.14 Looping Over a Grid
26.15 Grid Example: Get a Row
26.16 Data Structures Challenges
28.1 Game Design: Helicopter
22.1 Evolution Simulation

Indiana Computer Science III: Cybersecurity
Standard
23.5 Arrays and Objects
23.5 Arrays and Objects

Iowa Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Maryland Computer Science I
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Michigan Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

New Hampshire Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

New Jersey Computer Science
Standard
6.1 Intro to Lists/Arrays
6.2 Indexing Into an Array
6.5 Iterating Over an Array
6.6 Finding an Element in a List

New Jersey Computer Science and Design Thinking
Standard
6.1 Intro to Lists/Arrays
6.2 Indexing Into an Array
6.5 Iterating Over an Array
6.6 Finding an Element in a List

New Mexico Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Nevada Computer Science 2
Standard
7.2 Introduction to Arrays
7.3 Using Arrays
7.5 ArrayList Methods
7.6 Arrays vs ArrayLists
7.8 The List Interface
7.9 2D Arrays
7.11 HashMaps
7.12 Binary

Nevada Advanced Computer Science I
Standard
10.1 Intro to Lists/Arrays
10.2 Indexing Into an Array
10.3 Adding/Removing From an Array
10.4 Array Length and Looping Through Arrays
10.5 Iterating Over an Array
10.6 Finding an Element in a List
10.7 Removing an Element From an Array
10.9 Data Structures Quiz
11.2 Intro to Sets
11.3 Intro to Grids
11.4 Looping Over a Grid
11.5 Grid Example: Get a Row
16.1 Intro to Objects
16.4 Iterating Through an Object

North Carolina Intro to Computer Science (2020)
Standard
4.1 Intro to Lists/Arrays
4.2 Indexing Into an Array
4.5 Iterating Over an Array
4.6 Finding an Element in a List

Oklahoma Computer Science I
Standard
10.5 Arrays and Objects
10.5 Arrays and Objects

Oklahoma Computer Science II
Standard
9.1 Intro to Lists/Arrays
9.1 Intro to Lists/Arrays
9.2 Adding/Removing From an Array
9.2 Adding/Removing From an Array
9.3 Array Length and Looping Through Arrays
9.3 Array Length and Looping Through Arrays
9.4 Iterating Over an Array
9.4 Iterating Over an Array
9.5 Finding an Element in a List
9.5 Finding an Element in a List
9.6 Removing an Element From an Array
9.6 Removing an Element From an Array
17.1 Intro to Objects/Maps
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.7 Looping Over a Grid
17.1 Intro to Objects/Maps
17.2 Basics of Objects
17.3 Iterating Over an Object
17.4 When Do I Use an Object?
17.5 Intro to Sets
17.6 Intro to Grids
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row

Oklahoma Advanced Programming
Standard
5.1 Tuples
5.2 Lists
5.3 For Loops and Lists
5.4 List Methods
5.6 Dictionaries
13.1 Classes and Objects
13.5 Class Variables vs. Instance Variables
13.1 Classes and Objects
13.5 Class Variables vs. Instance Variables

Oklahoma Cybersecurity
Standard
13.5 Arrays and Objects
13.5 Arrays and Objects

Pennsylvania Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Rhode Island Computer Science Principles in Python
Standard
6.1 Tuples
6.2 Lists
6.3 For Loops and Lists
6.4 List Methods

South Carolina Computer Programming 2 with Python
Standard
4.1 Tuples
4.2 Lists
4.3 For Loops and Lists
4.4 List Methods
6.1 Classes and Objects
6.1 Classes and Objects
6.5 Class Variables vs. Instance Variables
6.5 Class Variables vs. Instance Variables
13.1 Project: Who Said It?
13.1 Project: Who Said It?

South Carolina Intermediate Computer Programming
Standard
4.1 Tuples
4.2 Lists
4.3 For Loops and Lists
4.4 List Methods
6.1 Classes and Objects
6.1 Classes and Objects
6.5 Class Variables vs. Instance Variables
6.5 Class Variables vs. Instance Variables
13.1 Project: Who Said It?
13.1 Project: Who Said It?

South Carolina Fundamentals of Computing
Standard
15.11 Intro to Lists/Arrays
21.9 Data Structures Challenges
21.8 Grid Example: Get a Row
21.7 Looping Over a Grid
21.6 Intro to Grids
21.5 Intro to Sets
21.4 When Do I Use an Object?
21.3 Iterating Over an Object
21.2 Basics of Objects
21.1 Intro to Objects/Maps
20.3 Removing an Element From an Array
20.2 Finding an Element in a List
15.14 Iterating Over an Array
15.13 Array Length and Looping Through Arrays
15.12 Adding/Removing From an Array
20.1 Indexing Into an Array
15.11 Intro to Lists/Arrays
21.9 Data Structures Challenges
21.8 Grid Example: Get a Row
21.7 Looping Over a Grid
21.6 Intro to Grids
21.5 Intro to Sets
21.4 When Do I Use an Object?
21.3 Iterating Over an Object
21.2 Basics of Objects
21.1 Intro to Objects/Maps
20.3 Removing an Element From an Array
20.2 Finding an Element in a List
15.14 Iterating Over an Array
15.13 Array Length and Looping Through Arrays
15.12 Adding/Removing From an Array
20.1 Indexing Into an Array

South Carolina Cybersecurity Fundamentals
Standard
16.5 Arrays and Objects
16.5 Arrays and Objects

South Carolina Fundamentals of Web Page Design and Development
Standard
7.8 Keyboard Interactions
8.2 Iterating with jQuery
10.2 Storing Data with Local Storage
10.3 Storing Data Structures with Local Storage
10.7 Storing Data with Firebase
10.10 For/In Loops
13.19 Intro to Lists/Arrays
13.20 Indexing Into an Array
13.21 Adding/Removing From an Array
13.22 Array Length and Looping Through Arrays
13.19 Intro to Lists/Arrays
13.20 Indexing Into an Array
13.21 Adding/Removing From an Array
13.22 Array Length and Looping Through Arrays

South Carolina Fundamentals of Web Page Design and Development with Certification Prep
Standard
7.8 Keyboard Interactions
8.2 Iterating with jQuery
10.2 Storing Data with Local Storage
10.3 Storing Data Structures with Local Storage
10.7 Storing Data with Firebase
10.10 For/In Loops
14.19 Intro to Lists/Arrays
14.20 Indexing Into an Array
14.21 Adding/Removing From an Array
14.22 Array Length and Looping Through Arrays
14.19 Intro to Lists/Arrays
14.20 Indexing Into an Array
14.21 Adding/Removing From an Array
14.22 Array Length and Looping Through Arrays

Tennessee Introduction to Computer Science
Standard
7.11 Intro to Lists/Arrays
7.11 Intro to Lists/Arrays
7.12 Adding/Removing From an Array
7.12 Adding/Removing From an Array
7.13 Array Length and Looping Through Arrays
7.13 Array Length and Looping Through Arrays
7.14 Iterating Over an Array
7.14 Iterating Over an Array

Texas Computer Science I
Standard
13.1 Intro to Arrays
13.2 Adding & Removing from an Array
13.3 Iterating Through an Array

Texas Foundations of Cybersecurity
Standard
20.5 Arrays and Objects

Virginia Computer Science Foundations
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

Washington Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array

IB Computer Science Standard Level
Standard
13.1 Array
13.2 Traversing Arrays
14.1 ArrayList
14.2 ArrayList Methods
14.3 Traversing ArrayLists

IB Computer Science Higher Level (Year One)
Standard
12.1 Array
12.2 Traversing Arrays
13.1 ArrayList
13.2 ArrayList Methods
13.3 Traversing ArrayLists

Utah Computer Programming 2
Standard
4.1 Tuples
4.1 Tuples
4.2 Lists
4.2 Lists
4.3 For Loops and Lists
4.3 For Loops and Lists
4.4 List Methods
4.4 List Methods
5.1 2d Lists
5.2 List Comprehensions
5.3 Packing and Unpacking
5.4 Dictionaries
8.1 Classes and Objects
8.1 Classes and Objects
8.5 Class Variables vs. Instance Variables
8.5 Class Variables vs. Instance Variables

Utah Computer Programming 1 and 2
Standard
12.1 Tuples
12.1 Tuples
12.2 Lists
12.2 Lists
12.3 For Loops and Lists
12.3 For Loops and Lists
12.4 List Methods
12.4 List Methods
13.1 2d Lists
13.2 List Comprehensions
13.3 Packing and Unpacking
13.4 Dictionaries
16.1 Classes and Objects
16.1 Classes and Objects
16.5 Class Variables vs. Instance Variables
16.5 Class Variables vs. Instance Variables

Introduction to Python Programming 2
Standard
4.1 Tuples
4.1 Tuples
4.2 Lists
4.2 Lists
4.3 For Loops and Lists
4.3 For Loops and Lists
4.4 List Methods
4.4 List Methods
5.1 2d Lists
5.2 List Comprehensions
5.3 Packing and Unpacking
5.4 Dictionaries
9.5 Class Variables vs. Instance Variables
13.1 Project: Who Said It?
9.1 Classes and Objects
9.1 Classes and Objects
9.5 Class Variables vs. Instance Variables
13.1 Project: Who Said It?

Utah Web Development 2
Standard
1.8 Keyboard Interactions
4.2 Storing Data with Local Storage
4.3 Storing Data Structures with Local Storage
4.7 Storing Data with Firebase
4.10 For/In Loops
8.19 Intro to Lists/Arrays
8.20 Indexing Into an Array
8.21 Adding/Removing From an Array
8.22 Array Length and Looping Through Arrays
8.19 Intro to Lists/Arrays
8.20 Indexing Into an Array
8.21 Adding/Removing From an Array
8.22 Array Length and Looping Through Arrays
9.2 Iterating with jQuery

Utah Web Development 1 and 2
Standard
6.8 Keyboard Interactions
9.2 Storing Data with Local Storage
9.3 Storing Data Structures with Local Storage
9.7 Storing Data with Firebase
9.10 For/In Loops
12.19 Intro to Lists/Arrays
12.20 Indexing Into an Array
12.21 Adding/Removing From an Array
12.22 Array Length and Looping Through Arrays
12.19 Intro to Lists/Arrays
12.20 Indexing Into an Array
12.21 Adding/Removing From an Array
12.22 Array Length and Looping Through Arrays
13.2 Iterating with jQuery

Texas Computer Science 2
Standard
7.2 Introduction to Arrays
7.2 Introduction to Arrays
7.3 Using Arrays
7.3 Using Arrays
7.5 ArrayList Methods
7.5 ArrayList Methods
7.6 Arrays vs ArrayLists
7.6 Arrays vs ArrayLists
7.8 The List Interface
7.8 The List Interface
7.9 2D Arrays (Matrices or Grids)
7.9 2D Arrays (Matrices or Grids)
7.11 HashMaps
7.11 HashMaps
7.12 Binary
7.12 Binary

Introduction to Artificial Intelligence (2021)
Standard
6.1 Tuples
6.1 Tuples
6.2 Lists
6.2 Lists
6.3 For Loops and Lists
6.3 For Loops and Lists
6.4 List Methods
6.4 List Methods
6.5 2d Lists
6.5 2d Lists
6.6 Dictionaries
6.6 Dictionaries

Fundamentals of Cybersecurity (2020)
Standard
4.5 Arrays and Objects
4.5 Arrays and Objects

Connecticut Foundations of Computer Science
Standard
9.11 Intro to Lists/Arrays
9.11 Intro to Lists/Arrays
9.12 Adding/Removing From an Array
9.12 Adding/Removing From an Array
9.13 Array Length and Looping Through Arrays
9.13 Array Length and Looping Through Arrays
9.14 Iterating Over an Array
9.14 Iterating Over an Array
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
17.9 Data Structures Challenges
16.1 Indexing Into an Array
17.9 Data Structures Challenges
17.8 Grid Example: Get a Row
17.7 Looping Over a Grid
17.6 Intro to Grids
17.5 Intro to Sets
17.4 When Do I Use an Object?
17.3 Iterating Over an Object
17.2 Basics of Objects
17.1 Intro to Objects/Maps
16.3 Removing an Element From an Array
16.2 Finding an Element in a List
16.1 Indexing Into an Array