Home/Second Grade Math/Lesson 119
K-5 friendly lesson
One small step at a time.Read the idea, try the activity, and celebrate each win as you go.

Add 3-Digit Numbers with Models (No Regrouping)

🧱 Welcome to the Big City! It's time to draw Flats, Rods, and Cubes to stack three giant columns of blocks together.

Do this: Read the concept below, then try the quiz or activity.

Lesson 119 of 186

Concept

We stacked tens and ones blocks before. Now we just add the giant square Flats to the far left!

🎯 The "Triple Stack" Method:
Example: 234 + 152 = ?
1. Draw the starting number (234):
   * Hundreds: Draw 2 giant squares.
   * Tens: Draw 3 long rods.
   * Ones: Draw 4 tiny dots. 
2. Draw the second number underneath (152):
   * Hundreds: 1 giant square.
   * Tens: 5 long rods.
   * Ones: 2 tiny dots.
3. Count the columns! (RIGHT TO LEFT!)
   * Count Ones dots: 4 + 2 = 6 ones.
   * Count Tens rods: 3 + 5 = 8 tens.
   * Count Hundreds squares: 2 + 1 = 3 hundreds.
4. Answer: 386.

The blocks make it impossible to get lost.

Try it

Build the giant skyline!

Instructions: Imagine the Giant squares (100), Long rods (10), and Tiny cubes (1). Count them column by column to find the answer.

Problem 1: 415 + 243 = ? * Squares: 4 + 2 = ___ * Rods: 1 + 4 = ___ * Cubes: 5 + 3 = ___ * Answer: ___

Problem 2: 152 + 524 = ? * Squares: ___ * Rods: ___ * Cubes: ___ * Answer: ___

Problem 3: You see a picture: Top row has 3 squares, 0 rods, 6 cubes. Bottom row has 1 square, 4 rods, 2 cubes. * Answer: ___

Problem 4: 500 + 192 = ? * (Hint: The top number only has squares!) * Answer: ___

Complete & Continue β†’