Kindergarten · Math · week 21

Building 17, 18, 19 and writing teen numbers

Build the numbers 17 through 19 using ten-frames or grouping, and correctly write the teen numerals.

Time to finish the teens. Seventeen, eighteen, and nineteen are all a full ten plus a lot of extra ones, 7, 8, or 9 more.

Writing teen numbers can be tricky because you hear the ones part first, like "seven-teen," but you write the ten digit first. Watch closely as we write them.

📋 For the teacher
Teach it (10–15 min):
  • Slow down on writing. Say one, then eight, as you write 18, out loud, every time.
  • Point out that the sound of the word (eight-teen) is backward from how we write it (1 then 8).
  • Keep building with objects alongside writing. Do not let writing replace the concrete model yet.
  • Praise correct number order even if the numeral shapes are still wobbly.
Talk about it:
  • What is tricky about writing teen numbers?
  • How many tens are in 17? In 19?
  • Can you build 19 and then write the numeral?

Mastery looks like: They build 17, 18, and 19 with objects and correctly write all three teen numerals in the right digit order.

Common stumbles: Writing the ones digit before the tens digit, such as writing 81 for eighteen; building an incomplete ten before adding extras.

See it visually

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

Counting & Ten-FramesCount objects in ten-frames and base-ten blocks, one tap at a time.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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