Fun with Math: Halves, Number Rules, and Regrouping!

Math Grades 1st Grade 47:53 Video
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Lesson Description

This lesson helps 1st graders learn about halves, finding missing numbers using rules, regrouping in addition, and comparing numbers.

Video Resource

Math Lessons for 1st Grade | Distance Learning for Kids | Kids Academy

Kids Academy

Duration: 47:53
Watch on YouTube

Key Concepts

  • Halves: Understanding equal parts of a group.
  • Number Rules: Using addition and subtraction to find missing numbers.
  • Regrouping: Combining ones to make tens when adding.
  • Comparing Numbers: Understanding greater than and less than
  • Addition and Subtraction Word Problems
  • Counting Back Subtraction Strategy
  • Counting from 100 to 120

Learning Objectives

  • Students will be able to divide a group of objects into two equal halves.
  • Students will be able to identify the rule in a number pattern and find the missing number.
  • Students will be able to regroup ones into tens when adding two-digit numbers.
  • Students will be able to compare two-digit numbers and identify which number is greater and which number is less than
  • Students will be able to solve addition and subtraction word problems.
  • Students will be able to utilize the counting back subtraction strategy
  • Students will be able to count from 100 to 120.

Educator Instructions

  • Introduction (5 mins)
    Start by asking students what they already know about halves, addition, subtraction, and comparing numbers. Show pictures of objects and ask students to identify half of the objects.
  • Halves Activity (10 mins)
    Explain the concept of dividing a group into two equal parts. Use examples like sharing snacks equally between two friends. Provide practice problems with drawings of objects (like the Cinderella slippers in the video) and have students draw a line to show halves.
  • Number Rule Game (15 mins)
    Introduce the idea of 'number machines' and rules. Present simple equations like 5 + ? = 7 or 10 - ? = 6. Have students figure out the missing number. Start with addition and subtraction within 10, then increase the difficulty.
  • Regrouping with Blocks (20 mins)
    Explain regrouping using base-ten blocks (or drawings of them). Show how 10 ones can be traded for 1 ten. Work through examples like 15 + 8, showing how to combine the ones, regroup, and then add the tens.
  • Comparing Numbers Activity (20 mins)
    Explain the concept of comparing numbers using a number line. Give students worksheets with two-digit numbers and have them circle the number that is greater or less than.
  • Word Problem Solving (20 mins)
    Read word problems aloud as a class. Underline important information in the word problem. Ask students to draw pictures to help them imagine and solve the word problem. Talk about how to identify clues in the word problem, like total or left over.
  • Subtraction Counting Back (20 mins)
    Explain the subtraction counting back method. Provide students with subtraction problems that they will solve using the method. Reinforce the method by having students touch their chin and count backwards using fingers to assist with finding the answer.
  • Counting Past 100 (20 mins)
    Reinforce the skill of counting from 100 to 120 by following the pattern of 1 to 20. Provide students with a challenge of counting from a number between 100 and 120 to 120. Assist the students with finding the pattern.
  • Review and Wrap-up (5 mins)
    Review the concepts covered in the lesson. Ask students to share what they learned and answer any remaining questions.

Interactive Exercises

  • Online Halves Game
    Use an interactive website or app where students can practice dividing groups of objects in half.
  • Number Machine Worksheet
    Create a worksheet with different number machines and rules, having students fill in the missing input or output numbers.
  • Base-Ten Block Addition
    Give students addition problems and have them use base-ten blocks to model the regrouping process.
  • Number Line Game
    Give students a number line and problems that require them to use the number line, like find a number between 10 and 20.
  • Addition and Subtraction Puzzles
    Give students addition and subtraction puzzles to reinforce their understanding.
  • Counting Back Game
    Play a game with the students that requires them to count back. Each time a student is able to count back successfully, they get a point.
  • Number Pattern Game
    Play a game with the students to reinforce the patterns and to help students reinforce numbers.

Discussion Questions

  • What does it mean to divide something in half?
  • Can you give me an example of when you need to find a missing number in math?
  • Why is regrouping important when we add big numbers?
  • What is a number line?
  • Can you think of a time when you had a problem that addition or subtraction helped to solve?
  • What's an easy way to remember how to count backward?
  • Can you come up with a pattern to help me count.

Skills Developed

  • Problem-solving
  • Critical thinking
  • Number sense
  • Pattern Recognition
  • Number Recognition

Multiple Choice Questions

Question 1:

What is half of 4 apples?

Correct Answer: 2 apples

Question 2:

In the number machine, if the rule is '+ 2' and the input is 5, what is the output?

Correct Answer: 7

Question 3:

If you have 13 ones, how many tens and ones can you make after regrouping?

Correct Answer: 1 ten and 3 ones

Question 4:

Which number is bigger, 25 or 15?

Correct Answer: 25

Question 5:

You have 5 cookies and your friend gives you 3 more. How many cookies do you have in all?

Correct Answer: 8 cookies

Question 6:

Use counting back! What's 8 - 2?

Correct Answer: 6

Question 7:

Let's count on. What number comes right after 115?

Correct Answer: 116

Question 8:

What is half of 6?

Correct Answer: 3

Question 9:

If the number machine rule is subtract 3 and the input number is 7, what is the output?

Correct Answer: 4

Question 10:

What is 23 + 4?

Correct Answer: 27

Fill in the Blank Questions

Question 1:

If you cut a pizza into two equal parts, each part is called a ______.

Correct Answer: half

Question 2:

In the number pattern 2, 4, 6, ____, 10, the missing number is ____.

Correct Answer: 8

Question 3:

When adding 17 + 5, you can regroup 10 ones to make 1 ____.

Correct Answer: ten

Question 4:

The sign > means ____ than.

Correct Answer: greater

Question 5:

A ____ problem uses words to describe a math question.

Correct Answer: word

Question 6:

I use my ____ to help me count backwards.

Correct Answer: fingers

Question 7:

I can use a ____ to help me recognize patterns.

Correct Answer: pattern

Question 8:

Half of 8 is ____.

Correct Answer: 4

Question 9:

If the input number is 4 and the machine number rule is 3, what is the number that you must add to get the output.

Correct Answer: 1

Question 10:

What is 13 + 3?

Correct Answer: 16

Educational Standards

CCSS.Math.Content.1.G.A.3:Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares. 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.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. CCSS.Math.Content.1.NBT.B.3:Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <. 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.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). CCSS.Math.Content.1.NBT.A.1:Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral.

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