K-5 friendly lesson
One small step at a time.Read the idea, try the activity, and celebrate each win as you go.
Use Models to Subtract 2-Digit Numbers (No Regrouping)
✂️ Cross out the blocks! When both numbers are two digits long, you have to cross out BOTH Tens-Rods and Ones-Cubes.
Do this: Read the concept below, then try the quiz or activity.
Lesson 64 of 186
Concept
Drawing pictures is brilliant for checking your work and seeing exactly what subtraction looks like.
🎯 The "Double Cross Out" Method: Example: 56 - 24 = ? 1. Draw the starting number (56): Draw 5 Tens-Rods and 6 Ones-Cubes. | | | | | . . . . . . 2. Cross out the Ones first! Subtraction number is 24. It has 4 ones. Cross out 4 little dots with X's. (You have 2 dots safe). 3. Cross out the Tens next! The number is 24. It has 2 tens. Cross out 2 long Rods with X's! (You have 3 Rods safe). 4. Count the survivors! You have 3 Rods and 2 Cubes perfectly safe. 5. Answer: 32!
You "subtracted 24" physically!
Try it
Double cross-out time!
Instructions: Imagine the big blocks and little blocks for the first number. Cross out the the blocks from the second number to find the answer.
Problem 1: 48 - 15 = ? * Model: 4 Rods, 8 Cubes. * Cross out 5 Cubes. (Leaves ___) * Cross out 1 Rod. (Leaves ___) * Answer: ___ Rods and ___ Cubes = ___
Problem 2: 67 - 32 = ? * Answer: ___
Problem 3: 89 - 56 = ? * Answer: ___
Problem 4: 25 - 11 = ? * Answer: ___