Fourth Grade · Math · week 12

Area model: 1-digit x 3-digit

Multiply a 1-digit number by a 3-digit number using an area model with three partial products.

The same idea from last week just grows by one more piece. Split the 3-digit number into hundreds, tens, and ones, multiply each part by the 1-digit number, then add all three partial products.

If one of the digits happens to be a zero, that partial product is simply zero, but the place still has to be accounted for.

📋 For the teacher
Teach it (10–15 min):
  • Draw three strips this time (hundreds, tens, ones) instead of two, keeping each partial product clearly labeled.
  • When a digit is zero, still write that partial product as 0 rather than skipping the step entirely.
  • Keep the partial products lined up vertically by size so adding all three is easy to check.
  • Ask how many partial products a problem like this needs before starting, so the plan is clear up front.
Talk about it:
  • How many partial products does a 1-digit by 3-digit problem need?
  • What happens to the middle partial product when there is a 0 in the tens place?
  • How is this like last week model, just with one more piece?

Mastery looks like: They multiply a 1-digit number by a 3-digit number using three partial products and add them correctly.

Common stumbles: Dropping the partial product for a zero digit instead of keeping it as a placeholder; misaligning place value when adding three partial products.

See it visually

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

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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