Teen Numbers Lab

Pick a number from 11 to 19 and see how it is built from one ten and some ones. Record the decomposition in a table and find the pattern that shows up in every teen number.

Guided Experiment: Teen Numbers Place Value Investigation

Look at the numbers 11, 12, 13, 14, 15, 16, 17, 18, 19. Do you think every teen number has the same structure? Predict how each teen number is built from tens and ones.

Write your hypothesis in the Lab Report panel, then click Next.

Build a Teen Number

Pick a Teen Number
13 is 1 ten and 3 ones.
The name of 13 contains its ones word.

Place Value Diagram

1 Ten
+
3 Ones
13 = 10 + 3

Controls

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Reference Guide

What Is a Teen Number

Teen numbers are the numbers from 11 to 19. Every teen number is made from one group of ten and some extra ones.

15 = 10 + 5

The ten is always there. The ones change from 1 all the way up to 9 as the number grows.

Place Value

In a two-digit number, the left digit tells the tens and the right digit tells the ones. Every teen number has a 1 in the tens place.

17 has 1 ten and 7 ones.
13 has 1 ten and 3 ones.
10 has 1 ten and 0 ones.

Place value is the idea that the spot where a digit sits tells you how much it is worth.

Special Names

The numbers 11 and 12 have the special names eleven and twelve. You cannot hear the ones digit in these names.

11. Eleven. Hidden ones.
12. Twelve. Hidden ones.
13 to 19. Names end with teen.

From 13 onward, each number says its ones digit right in the name. Thirteen has a three, fourteen has a four, and so on.

Why It Matters

Teen numbers are the first time students see two-digit numbers. Learning the ten plus ones pattern sets up all the bigger numbers that come later.

Big idea. If you can read 1 ten and 4 ones as 14, you can read 3 tens and 4 ones as 34, and 5 tens and 4 ones as 54.

Place value is the backbone of addition, subtraction, and every number you write down.