Fourth Grade · Math · week 11

Area model: 1-digit x 2-digit

Multiply a 1-digit number by a 2-digit number using an area model that splits the 2-digit number into tens and ones.

Break the 2-digit number into tens and ones, multiply each part by the 1-digit number separately, then add the two results together. This is exactly like finding the area of two smaller rectangles side by side.

Each smaller multiplication is one you already know how to do; the area model just organizes them so nothing gets lost.

📋 For the teacher
Teach it (10–15 min):
  • Draw an actual rectangle split into two pieces, tens and ones across the top, with the 1-digit factor down the side.
  • Label each smaller rectangle its own area (its partial product), then add the two areas for the total.
  • Point out this is the same area idea from measuring rectangles, just applied to multiplication.
  • This sets up the standard algorithm coming in a few weeks; it is the exact same math, just drawn out.
Talk about it:
  • Why do we split the 2-digit number into tens and ones?
  • What do the two smaller rectangles represent?
  • How does this area model connect to something you already know about area?

Mastery looks like: They multiply a 1-digit number by a 2-digit number by splitting into tens and ones and adding the partial products.

Common stumbles: Forgetting to multiply the ones part and only doing the tens part; adding the two partial products incorrectly.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →MultiplicationEqual groups and arrays make products finally click.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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