Counting Numbers 1 to 20

Counting up to 20 is the next big step after learning to count up to 10. Once a student can count and recognize numbers 1 through 10 confidently, the goal shifts to extending that same skill into the "teen" numbers (11 to 19) and finally to 20. This lesson breaks the process into small, visual steps so counting past ten feels just as natural as counting to ten did.

Counting up to 20 means being able to say and recognize the numbers 1, 2, 3, all the way through 20, in the correct order, and knowing that each number represents one more than the number before it. It also means being able to count a group of up to 20 real objects, pointing to one object per number so nothing gets counted twice or skipped.

This builds directly on counting up or down up to 10, since the numbers 1 to 10 stay exactly the same. What changes is what happens after 10.

The trickiest part of counting to 20 is usually the teen numbers, because their names do not always match their structure right away. Every teen number is really just 10 plus some extra ones. For example, 17 is 10 and 7 more: \( 10 + 7 = 17 \). Seeing this with objects helps the idea stick.

This same pattern works for every teen number: 11 is 10 and 1 more, 15 is 10 and 5 more, 19 is 10 and 9 more. Once a full ten-frame is "locked in" as 10, the rest of the count is just the small numbers already known from counting to 10.

A number line laid out from 1 to 20 gives a clear picture of the whole counting sequence in order. Moving one step to the right always means one more, and moving one step to the left always means one less.

Practicing with a shorter line first, like the one used for number lines up to 10, makes it easier to trust the pattern once the line stretches all the way to 20.

Being able to count forward from any starting number (say, from 8 up to 20) and backward from 20 down to 1 strengthens the sense of order between numbers. This skill connects closely with counting forward and backward, where the same forward and backward movement is practiced with smaller ranges before stretching to 20.

Suppose there are 16 stars drawn on a page, and the task is to count them.

1. Point to the first star and say "1," then move to the next star and say "2," continuing one number per star.
2. Group the first 10 stars mentally as a full ten-frame worth, so the count reaches "10" exactly when the tenth star is touched.
3. Keep counting the remaining stars starting from 11: "11, 12, 13, 14, 15, 16."
4. The last number said, 16, is the total number of stars, since \( 10 + 6 = 16 \).

Recording the count with simple marks, as practiced in tally marks up to 10, is another helpful way to check that every object was counted exactly once, then extending the same idea past ten.

• Always touch or move each object as it is counted so none are skipped or counted twice.
• Use a ten-frame to "anchor" the number 10 before continuing into the teens.
• Say the numbers out loud in order, pausing at 10 to notice the pattern change into "eleven, twelve, thirteen."
• Practice counting backward from 20 to build a complete sense of the sequence in both directions.

Related lessons

• Kindergarten