Numbers to 20: Counting, Writing, and How Many
A 30-minute math lesson for the youngest grades on what a number actually means: counting objects one at a time, knowing that the last number said is how many there are, and writing the numerals to 20.
Math
Subject
Grades K-1
Grade Level
30 minutes
Duration
Counting and Numbers
Topic
On this page: Materials · Warm-Up · Direct Instruction · Guided Practice · Independent Practice · Assessment · Closure · Related Resources
Learning Objectives
By the end of this lesson, students will be able to:
- Count a group of up to 20 objects, touching each one exactly once
- Answer how many without starting the count over
- Match a spoken number, a written numeral, and a group of that many things
- Write the numerals 0 to 20 in order
- Say which of two small numbers is more
Materials
- Counting to 5 Worksheet — Kindergarten (Basic), one copy per student
- Counting to 20 Worksheet — Kindergarten (Challenge), for the students who are ready
- Number Posters 0-20 printable, on the wall before the lesson
- Counters — cubes, buttons, or beans — about 25 per pair
- Small paper plates or trays, one per pair, so a counted group has somewhere to go
Vocabulary
- Count — to say the number words in order while touching one thing at a time
- How many — the total number of things in a group
- Number — how many there are
- Numeral — the written symbol for a number, like 7
- More — a bigger amount
- Fewer — a smaller amount
Preparation
Put the number posters up before the lesson, at the children’s eye level rather than above the board. A poster a five-year-old has to tip their head back to read is a poster they stop using by the second week.
Count out the counters into bags in advance, and make the amounts uneven — 12 in one, 17 in another, 9 in a third. If every pair has the same number, the answer travels around the room and no one has to count anything.
Have plates or trays ready. Moving each counted object onto a plate is what turns one-to-one correspondence from an instruction into something the hands do automatically, and it is the single most useful thing on the materials list.
Warm-Up
4 minutes. Count to 20 together as a class, out loud, twice. Everyone can do this and it should feel easy — that is the point of putting it first.
Then put seven counters on the table where everyone can see and ask a volunteer to find out how many. Watch what they do rather than listening to what they say. A child who touches each one once and stops has the skill. A child who says the words faster than their finger moves does not, and this is where you find that out.
Ask the class a second question about the same seven, without recounting: how many are there? Some children will start again from one. Notice who; do not correct it yet.
Direct Instruction
8 minutes. Model counting slowly and deliberately, moving each counter onto a plate as you say its number. Say the rule as you go: one word, one thing. Then do it wrong on purpose — say two numbers for one counter, then skip one — and let the class catch you. Being the one who spots the mistake fixes the rule far better than being told it.
Now the part that is actually being taught. Count nine counters, stop, and ask how many? Answer it yourself without recounting: nine — the last number I said is how many there are. Say that sentence twice. It is the whole lesson in eleven words, and it is the thing that separates a child who can chant from a child who can count.
Match the three forms. Hold up the group, point to the numeral on the poster, and say the word: nine things, the numeral 9, the sound "nine." Do four numbers this way. Children need all three tied together, because they routinely have two of the three and no link between them.
Finish on the teen numbers, and be honest about why they are hard. Point at 14 and say it out loud: we say four first and write the 1 first, and the number does not tell you that. Eleven and twelve do not even try. Tell the class these are the tricky ones for everybody — a child who thinks they are the only one writing 41 for fourteen stops trying.
Guided Practice
8 minutes. Pairs get a bag of counters and a plate. One child counts the bag onto the plate while the other watches for one word, one thing. Then they swap bags with another pair and do it again.
After each count, the watcher asks the counter one question and only this question: how many? If the counter starts over, the pair counts that bag again together. This is the entire drill, and it is worth the eight minutes.
Circulate and watch hands, not answers. What you are looking for is:
- a finger that touches every object exactly once
- a mouth that stays with the finger instead of running ahead
- an answer to “how many” that comes without a recount
A child who has all three is ready for the Challenge sheet today. A child who has the first two but not the third does not need bigger numbers — they need the same question asked more often, which costs nothing.
Independent Practice
6 minutes. Students work the Counting worksheet at the level that fits: counting to 5 for children still building one-to-one correspondence, counting to 20 for children who have it.
Leave the counters on the desk. A child who still needs to move objects to answer a printed question should move objects — taking the counters away does not create the skill, it just hides who does not have it yet.
Assessment
2 minutes. One at a time, quickly, as children finish: put out a small group of counters and ask them to count it, then ask how many?
You are recording one thing per child — whether the answer to the second question came without a recount. That single observation tells you more than a whole page of written answers, and it takes about ten seconds per child.
Closure
2 minutes. Hold up a group of counters and count it together as a class, slowly, one word one thing. Then ask the room how many, and let them answer without counting again. Close on the sentence the lesson was built around: the last number you say is how many there are.
Differentiation and Accommodations
- Extra support: work inside 5 and stay there as long as it takes. The counting to 5 worksheet is free with a member account, and a child who is solid to 5 will get to 20 far faster than a child who was rushed past it.
- Extension: the counting to 10 and counting to 20 sheets are the same lesson at a bigger range, and skip counting is the natural next step for anyone who finishes early.
- Common difficulty: the child who recounts every time. Do not tell them the answer — count with them, stop on the last number, and say it back as the total. Repeat it over several days rather than several minutes; this one arrives on its own schedule.
- Watch for: a numeral written backwards. At this age a reversed 3 or 7 is normal and is not a warning sign of anything. Show the correct form again and move on — making an issue of it teaches a child that writing numbers is dangerous.
Extension Activities
Tally marks are a good follow-up precisely because they group by fives, which gives a child a reason to count in something other than ones.
Adding within 20 is where this lesson is heading. A child who has cardinality can count on from a number instead of starting at one, and counting on is the first real addition strategy.
Count something real every day for a fortnight — children present, days until a holiday, books returned. Counting that answers a question the class actually had does more than any worksheet, and it costs a minute.
Counting coins is the other obvious counting context, and money lessons live with our sister site Money Instructor rather than here.
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