Lesson Plan
Number Line Detectives
Students will be able to use a number line to visually compare two numbers up to 100 and correctly write the greater than (>) or less than (<) symbol.
This lesson is important because understanding number relationships and being able to compare numbers is a foundational math skill that helps students develop number sense and problem-solving abilities. It also lays the groundwork for more complex mathematical operations.
Audience
2nd Grade
Time
20 minutes
Approach
Through visual exploration, guided practice, and an engaging game.
Prep
Teacher Preparation
10 minutes
Review the Number Line Detectives Slide Deck and practice the script. Gather materials for the Large Classroom Number Line Activity (e.g., masking tape on the floor or a long paper strip, number cards 0-100). Print and cut out the Mystery Number Cards Game. Print the Individual Number Lines Worksheet for each student.
Step 1
Warm-Up Review: What Do We Know About Numbers?
3 minutes
Begin with the Number Line Detectives Slide Deck (Slide 1-2).
Ask students to recall what a number line is and how we use it. Engage them with questions like:
- "What's the biggest number you know?"
- "What does 'greater than' mean? How about 'less than'?"
Step 2
Mini-Lesson: The Number Line as Our Detective Tool
5 minutes
Continue with the Number Line Detectives Slide Deck (Slide 3-5).
Introduce the concept of using a number line as a tool to visually compare numbers. Explain that the number further to the right on a number line is always greater. Demonstrate with a few examples using the slide deck. Introduce the 'greater than' (>) and 'less than' (<) symbols using a visual aid or hand motions.
Step 3
Guided Discovery: Human Number Line
7 minutes
Transition to the Large Classroom Number Line Activity.
Have students physically stand on or near a large number line (0-100) drawn on the floor or on a long strip of paper. Call out two numbers and have two students stand on those numbers. Ask the class to determine which number is greater or less by looking at their positions. Introduce the Mystery Number Cards Game and use a few pairs of cards for a quick demonstration. Guide students to correctly use the > or < symbols to compare the numbers.
Step 4
Practice Activity: Individual Number Line Investigations
3 minutes
Distribute the Individual Number Lines Worksheet.
Students will use their individual number lines to compare pairs of numbers and write the correct symbol (> or <) in the space provided. Circulate and provide support as needed.
Step 5
Share Out: Detective Debrief
2 minutes
Gather students back together.
Ask a few students to share their answers from the Individual Number Lines Worksheet. Discuss any challenges or interesting observations they made. Reiterate the main learning objective: using the number line to compare numbers.
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Slide Deck
Number Line Detectives: Comparing Numbers!
Are you ready to solve some number mysteries?
Welcome students to the lesson. Engage them by asking what they think a "number line detective" does.
What's a Number Line?
A line where numbers live in order!
- Numbers go from smallest to largest.
- It helps us see how numbers relate to each other.
Ask students: "What is a number line? What do we use it for?" Encourage them to share their prior knowledge. Prompt them to think about how numbers are ordered on a line.
Being a Number Line Detective
Our mission: Use the number line to compare two numbers!
Rule #1: The number further to the RIGHT is always GREATER.
Rule #2: The number further to the LEFT is always LESS.
Explain that today we'll use the number line to figure out which number is bigger or smaller. Emphasize that the further to the right a number is, the greater it is.
Our Detective Tools: Symbols!
Greater Than (>)
- The open mouth faces the bigger number!
Less Than (<)
- The pointy end faces the smaller number!
Introduce the symbols: Greater Than (>) and Less Than (<). Use the alligator analogy if helpful (the alligator always wants to eat the bigger number).
Let's Solve Some Mysteries!
Which symbol belongs in the middle?
- 15 ___ 20
- 50 ___ 30
- 72 ___ 70
- 8 ___ 81
Present these examples and ask students to determine the correct symbol. Use volunteers to point on an imaginary number line or refer to the classroom number line. Emphasize looking at positions.
Activity
Large Classroom Number Line Activity
Objective
Students will physically demonstrate number comparison on a large number line, identifying greater and less than relationships.
Materials
- Masking tape or a long strip of paper
- Markers
- Number cards (0-100, or a selection relevant to the lesson)
Instructions
-
Set Up the Number Line: Create a large number line on the classroom floor using masking tape or a long piece of paper. Mark out numbers from 0 to 100 at appropriate intervals. Ensure there's enough space for students to stand on or beside the numbers.
-
Introduce the Activity: Explain to students that they will become a "Number Line Detective" and help compare numbers by using their bodies on the number line.
-
Demonstrate: Call two students forward. Give each student a number card (e.g., 25 and 30). Have them stand on their respective numbers on the large classroom number line. Ask the class: "Which number is further to the right? Which number is greater? Which is less?" Guide them to use the correct terminology and symbols.
-
Guided Practice with Mystery Number Cards: Use a few pairs of Mystery Number Cards Game (which should be printed and cut out as per the lesson plan prep) for a quick demonstration with the full class.
-
Student Participation: Continue calling two different students forward, giving them new number cards. The rest of the class can observe and help determine the greater or lesser number, stating the comparison aloud (e.g., "30 is greater than 25"). Encourage students to explain why one number is greater or less based on its position on the number line.
-
Symbol Practice: After comparing, ask the class to show with their hands, or tell you, which symbol (>, <, or =) belongs between the two numbers. You can also have students write the symbol on individual whiteboards.
Worksheet
Individual Number Lines Worksheet
Name: _________________________ Date: _____________
Detective Challenge!
Use your number line to compare the numbers. Write the correct symbol (>, <, or =) in the box.
Part 1: Compare the Numbers
-
5
12 -
34
29 -
87
91 -
60
58 -
45
45 -
99
100 -
18
81 -
53
35
Part 2: Draw Your Own Number Line!
Draw a small number line (0-20) and show how you would compare the numbers 7 and 17.
Which number is greater? _________
Which number is less? _________
Game
Mystery Number Cards Game
Objective
Students will compare pairs of numbers using greater than (>) and less than (<) symbols, reinforcing their understanding of number order on a number line.
Materials
- Printed Mystery Number Cards (numbers 0-100)
- Pencils or markers
- Whiteboards or paper for writing symbols
Instructions
-
Preparation: Print and cut out the Mystery Number Cards. Create several pairs of cards (e.g., 23 & 32, 55 & 48, 9 & 90). For a full class game, you might prepare enough pairs for small groups to play simultaneously.
-
How to Play (Whole Class Demonstration):
- Show two Mystery Number Cards to the class (e.g., 42 and 24).
- Ask students: "Which number is further to the right on a number line?"
- Ask: "Which number is greater? Which is less?"
- Have students use their arms to form the correct symbol (>, <, or =) or write it on mini-whiteboards.
- Discuss their reasoning, referring back to the number line concept.
-
How to Play (Small Groups/Pairs):
- Divide students into small groups or pairs.
- Give each group a set of mixed Mystery Number Cards.
- One student draws two cards.
- Both students, or the group, must decide which symbol (>, <, or =) correctly compares the two numbers.
- They write down the comparison (e.g., 42 > 24).
- Students take turns drawing cards and comparing numbers.
- Optional: Students can earn a point for each correct comparison. The player or group with the most points at the end wins.
Answer Key
Answer Key: Individual Number Lines Worksheet
Part 1: Compare the Numbers
-
5 < 12
- Thought Process: On a number line, 5 is to the left of 12, meaning 5 is less than 12.
-
34 > 29
- Thought Process: On a number line, 34 is to the right of 29, meaning 34 is greater than 29.
-
87 < 91
- Thought Process: On a number line, 87 is to the left of 91, meaning 87 is less than 91.
-
60 > 58
- Thought Process: On a number line, 60 is to the right of 58, meaning 60 is greater than 58.
-
45 = 45
- Thought Process: Both numbers are the same, so they are equal.
-
99 < 100
- Thought Process: On a number line, 99 is to the left of 100, meaning 99 is less than 100.
-
18 < 81
- Thought Process: On a number line, 18 is far to the left of 81, meaning 18 is less than 81.
-
53 > 35
- Thought Process: On a number line, 53 is to the right of 35, meaning 53 is greater than 35.
Part 2: Draw Your Own Number Line!
Self-correction/Teacher discretion for drawing accuracy.
Example Number Line (0-20):
0 -- 1 -- 2 -- 3 -- 4 -- 5 -- 6 -- 7 -- 8 -- 9 -- 10 -- 11 -- 12 -- 13 -- 14 -- 15 -- 16 -- 17 -- 18 -- 19 -- 20
Which number is greater? 17
Which number is less? 7