📖

Subtracting 100 Mentally: Big Jumps Back

Mentally Adding and Subtracting 10 or 100

Day 144of 180
Week 29of 36
30Minutes
← Day 143Day 144 of 180Day 145 →
🖨️ Download Worksheet (PDF)🧮 Download Math Practice (PDF)
🎯 What You'll Learn

Learning Objectives

1

Subtract 100 from three-digit numbers mentally

2

Recognize the pattern of changing only the hundreds place

3

Develop confidence in mental math skills

📖 Scripture Connection

Proverbs 2:6

“For Yahweh gives wisdom. Out of his mouth comes knowledge and understanding.”

— Proverbs 2:6 (WEB)

Just as we learn mathematical patterns, God provides wisdom and understanding in our learning journey

📦 Materials Needed

  • Hundred chart
  • Base-ten blocks
  • Pencil
  • Worksheet
  • BibleMouse Grade 2 Math Resource Guide
📚 Step-by-Step

Lesson Plan

1Opening (5 min)

BibleMouse Math Adventure: Mental Subtraction Challenge

💭 Review Question: Can you remember how we subtract 10 from numbers yesterday?
2Teaching (10 min)

Introducing Subtracting 100 Mentally

📌 Key Talking Points:
  • When we subtract 100, only the hundreds place changes
  • 465 - 100 becomes 365
  • The tens and ones places stay exactly the same
💬 Discussion Questions:
  • What happens to a number when we subtract 100?
  • Can you show me how the hundreds place changes?
3Activity: 100 Subtraction Expedition (12 min)
worksheet

Complete BibleMouse mental subtraction worksheet

📝 Instructions:
  1. Look at each number
  2. Subtract 100 in your head
  3. Write the new number
  4. Check your work using base-ten blocks
🔄 Variations:

Simpler: Use hundred chart to track subtraction

Challenge: Solve problems without visual aids

4Closing (3 min)

Review mental subtraction strategy

📝 Review Questions:
  • What changes when we subtract 100?
  • Can you explain the pattern to me?

Coming up: Tomorrow we'll mix addition and subtraction of 10 and 100

👨‍👩‍👧 For Parents

Teaching Notes

📚 Background:

Mental math builds computational fluency and confidence

💡 Teaching Tips:
  • Use manipulatives to make abstract concepts concrete
  • Encourage thinking out loud
  • Celebrate effort, not just correct answers
🤔 Common Struggles:

Children might forget to keep tens and ones places unchanged

👀 Signs of Understanding:

Consistent application of subtraction pattern

🚀 Want More?

Extension Activities

  • Create a mental math game using dice
  • Practice subtraction with BibleMouse mental math cards

Ready for Tomorrow?

Great job completing today's lesson!

Continue to Day 145 →Back to Math