Gorilla Gym Math: Addition and Subtraction Fun!

Math Grades 1st Grade 5:31 Video
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Lesson Description

Learn addition and subtraction within 20 using fun word problems about gorillas and cookies! This lesson helps you understand how to solve number stories and write equations.

Video Resource

Exercising gorillas | Addition and subtraction within 20 | Early Math | Khan Academy

Khan Academy

Duration: 5:31
Watch on YouTube

Key Concepts

  • Addition and subtraction within 20
  • Solving word problems
  • Understanding the relationship between addition and subtraction
  • Using diagrams to solve problems

Learning Objectives

  • Students will be able to solve addition and subtraction word problems within 20.
  • Students will be able to represent word problems using equations with a symbol for the unknown number.
  • Students will be able to explain their reasoning when solving word problems.
  • Students will use diagrams to visualize and solve problems

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students if they have ever solved a math story problem. Briefly discuss what makes a story problem different from a regular math problem. Explain that today they will be learning how to solve fun math stories with gorillas and cookies!
  • Video Viewing (7 mins)
    Play the Khan Academy video "Exercising gorillas | Addition and subtraction within 20 | Early Math | Khan Academy". Encourage students to pay attention to how the person in the video solves the math stories.
  • Guided Practice: Gorilla Problem (8 mins)
    Revisit the first problem in the video about the gorillas. Have students draw the diagram on their own paper to help visualize the problem. Then, work together to write the equation represented by the problem. Discuss both addition and subtraction ways to solve it ( ___ + 3 = 17 and 17 - 3 = ___). Guide students to explain WHY each way works.
  • Guided Practice: Cookie Problem (10 mins)
    Revisit the second problem in the video about the cookies. Ask students to act out the problem using counters (like small blocks or erasers). Have them start with 13 counters, then take some away to leave 8 counters. How many did they take away? Work together to write the equation represented by the problem (13 - ___ = 8). Discuss different ways to solve (13 - 8 = ___ and 8 + ___ = 13). Guide students to explain their reasoning.
  • Independent Practice (10 mins)
    Provide students with 2-3 new word problems (see examples below). Have them draw pictures, write equations, and solve. Circulate to provide support as needed. * **Problem 1:** There were 9 birds sitting in a tree. Then, 6 more birds flew to the tree. How many birds are in the tree now? * **Problem 2:** Lily had 15 crayons. She gave 7 crayons to her friend. How many crayons does Lily have left? * **Problem 3:** Tom has 8 toy cars. Sarah has 5 more toy cars than Tom. How many toy cars does Sarah have?

Interactive Exercises

  • Act It Out!
    Provide students with simple props (counters, small toys). Read a word problem and have them physically act out the problem to find the solution.
  • Number Bond Fun
    Use number bonds to represent addition and subtraction problems. For example, for 8 + 5 = 13, students would fill in the number bond with 8, 5, and 13.

Discussion Questions

  • What is your favorite strategy for solving math stories?
  • How can drawing a picture help you solve a math story?
  • Can you think of a time when you used addition or subtraction in real life?

Skills Developed

  • Problem-solving
  • Critical thinking
  • Mathematical reasoning
  • Visual representation

Multiple Choice Questions

Question 1:

There are 7 apples on a tree. 4 apples fall down. How many apples are left on the tree?

Correct Answer: 3

Question 2:

You have 5 red balloons and 6 blue balloons. How many balloons do you have in all?

Correct Answer: 11

Question 3:

Kim has 12 stickers. She gives 3 to her friend. How many stickers does Kim have now?

Correct Answer: 9

Question 4:

What number is missing? 6 + ___ = 10

Correct Answer: 4

Question 5:

There are 14 birds. 5 fly away. How many are left?

Correct Answer: 9

Question 6:

What number is missing? 15 - ___ = 7

Correct Answer: 8

Question 7:

Ben has 8 cars. Sue has 4 cars. How many cars do they have together?

Correct Answer: 12

Question 8:

You have 11 cookies. You eat 2 cookies. How many cookies are left?

Correct Answer: 9

Question 9:

What is 9 + 7?

Correct Answer: 16

Question 10:

What is 16 - 4?

Correct Answer: 12

Fill in the Blank Questions

Question 1:

3 + 5 = ____

Correct Answer: 8

Question 2:

10 - 2 = ____

Correct Answer: 8

Question 3:

7 + ____ = 12

Correct Answer: 5

Question 4:

15 - ____ = 6

Correct Answer: 9

Question 5:

6 + 8 = ____

Correct Answer: 14

Question 6:

18 - 9 = ____

Correct Answer: 9

Question 7:

____ + 4 = 11

Correct Answer: 7

Question 8:

____ - 3 = 9

Correct Answer: 12

Question 9:

14 - 6 = ____

Correct Answer: 8

Question 10:

5 + 9 = ____

Correct Answer: 14

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.OA.D.8:Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ - 3, 6 + 6 = _. CCSS.Math.Content.1.OA.C.6:Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).

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