Growing or Shrinking? Adding and Subtracting Fun!

Math Grades 1st Grade 6:02 Video
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Lesson Description

Learn how to decide if you need to add or subtract to solve math problems! We'll use a simple trick to see if numbers are growing bigger or shrinking smaller to choose the right operation.

Video Resource

Addition and Subtraction for First Grade | Kids Academy

Kids Academy

Duration: 6:02
Watch on YouTube

Key Concepts

  • Addition makes numbers bigger.
  • Subtraction makes numbers smaller.
  • Comparing the first number and the answer helps decide whether to add or subtract.

Learning Objectives

  • Students will be able to determine whether to add or subtract in a given equation.
  • Students will be able to explain why they chose addition or subtraction based on whether the first number grows or shrinks to reach the answer.

Educator Instructions

  • Introduction (5 mins)
    Start by reviewing what addition and subtraction mean. Ask students: 'What happens when you add things together? Do you have more or less? What about when you subtract?' Briefly discuss examples like adding toys to a pile or eating some cookies.
  • Video Viewing (7 mins)
    Watch the Kids Academy video 'Addition and Subtraction for First Grade'. Encourage students to pay attention to the trick the teacher uses to decide whether to add or subtract.
  • Practice Together (8 mins)
    Work through a few example problems on the board as a class. Use the strategy from the video: 'Is the first number smaller or bigger than the answer? Is the number growing or shrinking?' For example: 5 _ 2 = 7 and 9 _ 4 = 5. Have students explain their reasoning.
  • Independent Practice (10 mins)
    Give students a worksheet with similar problems (e.g., 6 _ 3 = 9, 10 _ 2 = 8, 4 _ 4 = 0, 7 _ 1 = 8). Have them circle the + or - sign to complete each equation. Encourage them to use the 'growing or shrinking' trick.
  • Wrap-up (5 mins)
    Review the answers to the worksheet. Ask students to share any other tricks or strategies they use to decide whether to add or subtract. Emphasize that understanding whether a number is growing or shrinking is a helpful way to solve problems.

Interactive Exercises

  • Number Line Game
    Use a number line. Give students a starting number and an operation (+ or -) and another number. Have them hop along the number line to find the answer. For example: 'Start at 3, add 2.' or 'Start at 8, subtract 3.'
  • Object Manipulation
    Use small objects like blocks or counters. Give students a problem like 'Start with 6 blocks, add 3 more.' or 'Start with 10 blocks, take away 4.' Have them physically manipulate the objects to find the answer.

Discussion Questions

  • When do we use addition in our everyday lives?
  • When do we use subtraction in our everyday lives?
  • Can you think of a time you added something and got more?
  • Can you think of a time you subtracted something and got less?

Skills Developed

  • Addition and Subtraction
  • Problem-solving
  • Logical reasoning

Multiple Choice Questions

Question 1:

When you add, do numbers get bigger or smaller?

Correct Answer: Bigger

Question 2:

When you subtract, do numbers get bigger or smaller?

Correct Answer: Smaller

Question 3:

If you start with 5 and end up with 8, did the number get bigger or smaller?

Correct Answer: Bigger

Question 4:

If you start with 10 and end up with 6, did the number get bigger or smaller?

Correct Answer: Smaller

Question 5:

What sign do we use for addition?

Correct Answer: +

Question 6:

What sign do we use for subtraction?

Correct Answer: -

Question 7:

If 4 + 2 = 6, what sign goes in the blank? 4 ___ 2 = 6

Correct Answer: +

Question 8:

If 7 - 3 = 4, what sign goes in the blank? 7 ___ 3 = 4

Correct Answer: -

Question 9:

Which of these makes the number bigger?

Correct Answer: Adding

Question 10:

Which of these makes the number smaller?

Correct Answer: Taking away

Fill in the Blank Questions

Question 1:

When we add, the number gets ____.

Correct Answer: bigger

Question 2:

When we subtract, the number gets ____.

Correct Answer: smaller

Question 3:

The sign for addition is ____.

Correct Answer: +

Question 4:

The sign for subtraction is ____.

Correct Answer: -

Question 5:

If we start with a small number and want a big number, we should ____.

Correct Answer: add

Question 6:

If we start with a big number and want a small number, we should ____.

Correct Answer: subtract

Question 7:

5 + 3 = ____

Correct Answer: 8

Question 8:

9 - 2 = ____

Correct Answer: 7

Question 9:

Adding means putting things ____.

Correct Answer: together

Question 10:

Subtracting means taking things ____.

Correct Answer: away

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).

Teaching Materials

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