Build Teen Numbers

Overview

Students build on earlier learning about tens and ones by exploring teen numbers as one full ten and some ones. They use concrete materials, images and numerals to notice that changing the number of ones changes the total while the ten remains constant.

Learning intentions

• WALT make and read teen numbers.
• WALT show teen numbers using a ten and ones.
• WALT explain how a numeral, a model and a spoken number show the same amount.
• WALT compare teen numbers using mathematical language.

Success criteria

• I can build a teen number with one ten and some ones.
• I can write and read the matching numeral.
• I can say how many tens and ones are in my number.
• I can explain which of two teen numbers is greater and how I know.

Curriculum links

• Mathematics and Statistics — Number: develop understanding of numbers, quantities and how they are represented.
• Mathematics and Statistics — Number: compose, decompose, read and compare numbers within the appropriate early number range.
• Mathsteasers: use a reasoning challenge to deepen understanding and explain mathematical thinking.
• Mathematical communication and reasoning: represent ideas with materials, drawings, words and numerals.

Lesson structure (30 minutes)

1. 0–4 min · Notice and wonder. Teacher displays a ten rod and seven ones, then asks, “What number could this be? What do you notice?” Open with the hook and learning intention slides and accept children’s ideas without correcting immediately. Students turn and talk, then share what the materials might represent.

2. 4–9 min · Model teen numbers. Teacher explicitly builds 17, saying, “One ten and seven ones makes seventeen,” and records 10 + 7 = 17. Show 14 and 19, highlighting that the first digit tells us there is one ten and the second digit tells us the extra ones. Use the modelled examples and place-value visual to show the ten as a complete group. Students count the ones, match each model to a numeral and rehearse the sentence: “___ is one ten and ___ ones.”

3. 9–17 min · Pair build and match. Place students in pairs and give each pair number cards and rods. One child chooses a card from 11–19, builds it with one ten and ones, and says the sentence; the partner checks by counting and swaps roles. Provide the Twenty-frame Mats for pairs to build the same number in a second representation, write the numeral and record a simple addition sentence. Refer to the pair-task instructions and talk prompts. Students compare two numbers by asking, “Which has more ones?”, “Which is greater?” and “How do you know?”

4. 17–23 min · Change one part. Teacher models 13, then adds two ones and asks, “What changed? What stayed the same?” Repeat with 16 and 19. Invite children to make a teen number, then change only the ones to make a new number. Students record both numbers on the teen-number build and compare sheet by drawing or attaching a ten and ones, writing the numeral and circling the greater number. Encourage oral explanations rather than lengthy writing.

5. 23–27 min · Reasoning challenge. Teacher shows a ten rod and asks, “Can you make the greatest teen number using one ten and some ones? Can you make the smallest teen number?” Discuss 19 and 10, clarifying that 10 has one ten and zero ones. Then ask, “Is 18 greater than 15? What proves it?” Students use rods or their ten-frame to justify their answer to a partner. Challenge confident students to order 12, 17 and 19 and explain the pattern.

6. 27–30 min · Share and assess. Revisit the summary and exit-question slide. Ask several students to show a number between 10 and 19 and complete: “My number is ____. It has one ten and ____ ones.” Students complete the final item on the quick-check box or show their model to the teacher before packing away.

Resources

• Number cards showing 10–19
• Number rods or base-ten materials
• One ten-frame mat per pair
• the Twenty-frame Mats
• the teen-number build and compare sheet
• the teen-number teaching deck
• Pencils, crayons and mini whiteboards
• Floor or table space for paired work

Assessment

• Listen during modelling and pair work for accurate counting, one-to-one correspondence and use of “ten”, “ones”, “greater” and “less”.
• Check whether students connect the concrete model, spoken number and written numeral, especially for 10, 11 and 19.
• Use the final model-and-say response and worksheet quick-check to group students for the next lesson: secure, developing or needing further practice with teen numbers.

Differentiation

• Support children who need it with a visible ten rod, a smaller choice of cards such as 10, 11, 12 and 15, and the sentence frame “___ has one ten and ___ ones.” Let them touch and count each object.
• Pair children thoughtfully and allow drawing, pointing or speaking instead of writing full explanations. Model vocabulary with gestures and repeated oral language for children learning English or needing language support.
• For children ready for extension, ask them to order three or four teen numbers, find one more and one less, or explain why every teen number has one ten but a different number of ones.
• Keep the challenge within the early number range; do not require children to work with two-digit place-value notation beyond teen numbers.