Subtracting 1 and 10: Place Value Fun!

Math Grades 1st Grade 2:31 Video
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Lesson Description

Learn how subtracting 1 and 10 changes the ones and tens places using fun visuals!

Video Resource

Subtracting 1 vs. subtracting 10 | Addition and subtraction within 100 | 2nd grade | Khan Academy

Khan Academy

Duration: 2:31
Watch on YouTube

Key Concepts

  • Place Value (Tens and Ones)
  • Subtracting 1 affects the ones place
  • Subtracting 10 affects the tens place

Learning Objectives

  • Students will be able to identify the tens and ones place in a two-digit number.
  • Students will be able to subtract 1 from a two-digit number and explain how the ones place changes.
  • Students will be able to subtract 10 from a two-digit number and explain how the tens place changes.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they know about the numbers 1-99. Remind them that each number has a 'ones' place and that numbers 10 and bigger also has a 'tens' place. Introduce the idea that you can subtract from those numbers. Explain that today, they will learn how subtracting 1 and 10 changes a number by looking at the tens and ones places.
  • Video Viewing (7 mins)
    Play the Khan Academy video "Subtracting 1 vs. subtracting 10 | Addition and subtraction within 100 | 2nd grade | Khan Academy." Pause at key points to ask students questions and ensure understanding.
  • Guided Practice (10 mins)
    Work through example problems together on the board. Start with numbers like 35, 42, and 28. First, subtract 1 from each number, having students explain which place (tens or ones) changed and how. Then, subtract 10 from each number, again focusing on the place value changes.
  • Independent Practice (10 mins)
    Give students worksheets with similar subtraction problems. Encourage them to draw pictures of tens and ones to help visualize the changes.
  • Wrap Up (3 mins)
    Review the key concepts: subtracting 1 changes the ones place, and subtracting 10 changes the tens place. Ask students to give real-life examples where they might subtract 1 or 10 (e.g., taking one cookie or spending ten dollars).

Interactive Exercises

  • Place Value Blocks Activity
    Use base-ten blocks (ones and tens) to physically represent subtraction. Give students a number like 23. Have them remove 1 one block to subtract 1, and then remove 1 ten block to subtract 10. Ask them to state the new number.
  • Number Line Hop
    Use a number line. Start at a number and hop back 1 to subtract 1, or hop back 10 to subtract 10. Have students call out the new number after each hop.

Discussion Questions

  • What happens to a number when you take away 1?
  • What happens to a number when you take away 10?
  • Can you think of a time when you might need to subtract 1 or 10?

Skills Developed

  • Place Value Understanding
  • Subtraction Skills
  • Problem-Solving

Multiple Choice Questions

Question 1:

What number is in the ones place in the number 37?

Correct Answer: 7

Question 2:

What number is in the tens place in the number 52?

Correct Answer: 5

Question 3:

If you subtract 1 from 25, what number will you get?

Correct Answer: 24

Question 4:

If you subtract 10 from 48, what number will you get?

Correct Answer: 38

Question 5:

Which place changes when you subtract 1?

Correct Answer: Ones place

Question 6:

Which place changes when you subtract 10?

Correct Answer: Tens place

Question 7:

What is 63 minus 1?

Correct Answer: 62

Question 8:

What is 89 minus 10?

Correct Answer: 79

Question 9:

I have 4 tens and 6 ones. If I take away one one, what number do I have?

Correct Answer: 45

Question 10:

I have 7 tens and 2 ones. If I take away one ten, what number do I have?

Correct Answer: 62

Fill in the Blank Questions

Question 1:

In the number 19, the 9 is in the _____ place.

Correct Answer: ones

Question 2:

In the number 64, the 6 is in the _____ place.

Correct Answer: tens

Question 3:

When you subtract _____, only the ones place changes.

Correct Answer: 1

Question 4:

When you subtract _____, only the tens place changes.

Correct Answer: 10

Question 5:

32 minus 1 is _____.

Correct Answer: 31

Question 6:

55 minus 10 is _____.

Correct Answer: 45

Question 7:

The number 80 has _____ tens and 0 ones.

Correct Answer: 8

Question 8:

The number 47 has 4 tens and _____ ones.

Correct Answer: 7

Question 9:

78 - 1 = _____.

Correct Answer: 77

Question 10:

91 - 10 = _____.

Correct Answer: 81

Educational Standards

1.NBT.B.2:Understand that the two digits of a two-digit number represent amounts of tens and ones. 1.NBT.C.5:Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. 1.NBT.C.6:Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.

Teaching Materials

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