📏 Solving Length Word Problems: Adding and Subtracting Fun!

Math Grades 1st Grade 5:49 Video
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Lesson Description

Learn how to solve word problems about length using addition and subtraction. We'll use centimeters and meters to measure lines and objects!

Video Resource

Length word problems | Measurement and data | Early Math | Khan Academy

Khan Academy

Duration: 5:49
Watch on YouTube

Key Concepts

  • Addition
  • Subtraction
  • Length Measurement (centimeters and meters)
  • Word Problems

Learning Objectives

  • Students will be able to solve addition and subtraction word problems related to length.
  • Students will be able to understand and use centimeters and meters as units of length.
  • Students will be able to identify the correct operation (addition or subtraction) needed to solve a word problem.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they know about measuring length. What tools can we use? What units do we know (e.g., centimeters, meters)? Introduce the idea of using addition and subtraction to solve problems about length.
  • Video Viewing (7 mins)
    Watch the Khan Academy video 'Length word problems | Measurement and data | Early Math'. Encourage students to pay attention to how the narrator solves each problem.
  • Guided Practice (10 mins)
    Work through the examples from the video again as a class. Pause after each step and ask students to explain what is happening and why. Encourage them to draw pictures to help visualize the problems.
  • Independent Practice (10 mins)
    Give students similar word problems to solve on their own or in pairs. Provide assistance as needed. Examples: 1. A ribbon is 25 centimeters long. Another ribbon is 10 centimeters longer. How long is the longer ribbon? 2. A stick was 40 meters long. Someone broke off 15 meters. How long is the stick now?
  • Wrap-up (3 mins)
    Review the key concepts from the lesson. Ask students to share what they learned and how they can use these skills in real life.

Interactive Exercises

  • Classroom Measurement Scavenger Hunt
    Have students measure different objects in the classroom using rulers or meter sticks. Then, create word problems based on their measurements for classmates to solve. For example: 'The table is 60 centimeters long. The book is 20 centimeters long. How much longer is the table than the book?'
  • Length Story Creation
    Divide students into groups and have them create their own word problems about length. Each group can then share their problem with the class to solve.

Discussion Questions

  • What are some things we measure in centimeters and meters?
  • How do you know when to add or subtract in a word problem?
  • Can you think of a time you needed to measure something?

Skills Developed

  • Problem-solving
  • Critical thinking
  • Measurement
  • Addition and Subtraction

Multiple Choice Questions

Question 1:

Sara has a rope that is 10 centimeters long. John's rope is 5 centimeters longer. How long is John's rope?

Correct Answer: 15 centimeters

Question 2:

A pencil is 12 centimeters long. You sharpen it and now it is 10 centimeters long. How much shorter is the pencil now?

Correct Answer: 2 centimeters

Question 3:

A crayon is 8 centimeters long. Another crayon is 4 centimeters long. If you put them end to end, how long are they together?

Correct Answer: 12 centimeters

Question 4:

A book is 20 centimeters tall. A box is 30 centimeters tall. How much taller is the box?

Correct Answer: 10 centimeters

Question 5:

Lisa has a string that is 15 meters long. She cuts off 7 meters. How long is the string now?

Correct Answer: 8 meters

Question 6:

Tom has a toy car that is 9 centimeters long. He wants to make a line of cars that is 18 centimeters long. How many more centimeters of cars does he need?

Correct Answer: 9 centimeters

Question 7:

A blue block is 6 centimeters tall. A red block is 7 centimeters tall. If you stack them, how tall is the stack?

Correct Answer: 11 centimeters

Question 8:

A garden is 14 meters wide. Someone adds 5 meters to it. How wide is the garden now?

Correct Answer: 19 meters

Question 9:

Ben has a rope that is 17 centimeters long. He cuts it so its 8 centimeters long. How many centimeters did he cut off?

Correct Answer: 9 centimeters

Question 10:

A window is 5 meters wide. A door is 2 meters wide. How much wider is the window?

Correct Answer: 3 meters

Fill in the Blank Questions

Question 1:

A worm is 6 centimeters long. Another worm is 4 centimeters long. Together, they are ______ centimeters long.

Correct Answer: 10

Question 2:

A table is 50 centimeters long. Someone cuts off 10 centimeters. Now it is ______ centimeters long.

Correct Answer: 40

Question 3:

A paper is 20 centimeters long. A pencil is 5 centimeters longer. The pencil is ______ centimeters long.

Correct Answer: 25

Question 4:

A rug is 4 meters long. A room is 8 meters long. The room is ______ meters longer than the rug.

Correct Answer: 4

Question 5:

A line is 12 centimeters long. Another line is 3 centimeters shorter. The shorter line is ______ centimeters long.

Correct Answer: 9

Question 6:

A building is 25 meters tall. Another building is 10 meters taller. The new building is ______ meters tall.

Correct Answer: 35

Question 7:

Jill has 10 centimeters of ribbon. She uses 4 centimeters. She now has ______ centimeters of ribbon.

Correct Answer: 6

Question 8:

Ken has 5 meters of yarn. Jan gives him 7 meters. Now Ken has ______ meters of yarn.

Correct Answer: 12

Question 9:

A desk is 70 centimeters long. A chair is 30 centimeters long. The desk is ______ centimeters longer than the chair.

Correct Answer: 40

Question 10:

A toy is 11 centimeters tall. Someone takes 5 centimeters off. The toy is now ______ centimeters tall.

Correct Answer: 6

Educational Standards

CCSS.Math.Content.1.OA.A.1:Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem. CCSS.Math.Content.1.MD.A.2:Express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps. Limit to contexts where the object being measured is spanned by a whole number of length units with no gaps or overlaps. CCSS.Math.Content.1.NBT.C.4:Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

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