Understanding Number 20

Overview

This lesson is part of the Year 1 maths curriculum and explores understanding numbers up to 20. Specifically, this aligns with the National Curriculum for Mathematics - Number and Place Value (KS1). By the end of the session, students will:

• Represent, count, and order numbers up to 20.
• Recognise one more and one less than 20.
• Begin to identify the number 20 as two groups of ten.

The lesson will include hands-on exploration, active group work, and independent problem-solving to engage young learners and cater to diverse learning styles.

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Learning Objectives

By the end of the 45-minute session, pupils will:

1. Recognise and say the number 20 confidently.
2. Represent the number 20 using objects, visual models, and numerals.
3. Compare numbers, identifying one more and one less than 20.
4. Understand the concept of 20 as two full groups of ten and link this to place value.

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Resources Needed

• A large number line (displayed at the front).
• 20 multi-coloured counters per child.
• Place value counters or base ten blocks (if available).
• Whiteboards and markers.
• Pre-cut paper “ten frames” (two per child).
• A number bingo sheet for numbers 10–20 (teacher provided).
• Flashcards with numerals and dots (0–20).
• A soft ball for a warm-up game.

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Lesson Structure

1. Starter Activity: Number Warm-Up (5 minutes)

Objective: Pupils feel energised and ready for the session with a fun oral activity.

• Begin with a whole-class game of “Quick Count Pass”.
  • Stand in a circle with the students. Pass a soft ball around. Each child must say a number, starting from 10 and aiming to reach 20.
  • If a child hesitates or says the wrong number, everyone claps and starts again from 10.
  • Reinforce correct pronunciations and sequencing.
• Ask the class: “What is the biggest number we’ve said so far? Is 20 bigger or smaller than 15?” (Build a sense of curiosity about 20.)

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2. Teaching Input: Exploring the Number 20 (10 minutes)

Objective: Pupils understand the number 20 and see it represented in multiple ways.

1. Visual Demonstration:

   • Show a physical number line (0–20) and highlight the number 20 on it.
   • Explain: “20 is very special—it's the biggest number we’re working on this year in maths!”
   • Show that 20 is 10 more than 10 by adding groups of ten counters.

2. Practical Modelling:

   • Use two ten frames on the board and fill them with counters to represent 20.
   • Say: "20 is two full ten frames. Each ten frame is a group of ten."

3. Link to Real Life:

   • Hold up everyday objects, e.g., 20 pencils or 20 buttons, and have the children count them aloud as a class.
   • Ask: "Can you think of something else in the real world we might have 20 of?"

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3. Group Activity: Hands-On Counting with Ten Frames (15 minutes)

Objective: Pupils independently explore 20 using hands-on resources.

• Hand out two pre-cut ten frames and 20 counters to each child.
• Say: “I want you to show me one group of 10. Now show me two groups of 10. What number do we have?”
• Encourage them to fill both ten frames and explain: “20 is two groups of 10.”
• Facilitate exploration:
  • “What happens if I want 1 more? What number do I have now?”
  • “What about 1 less?”
  • Provide question prompts for pupils to explore with their pair.

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4. Independent Practice: Number Comparisons (10 minutes)

Objective: Pupils develop confidence identifying 20 and numbers one more/less than 20.

• Distribute individual whiteboards and markers.

• Call out instructions for pupils to complete quickly:

  • “Write the number that is one more than 19. Show me!”
  • “What is one less than 20?”
  • “Draw 10 counters. Now draw another 10 counters. What number do you have?”

• Challenge Extension: For confident students, introduce vocabulary such as “equal to,” “greater than,” and “less than.” Provide comparison questions: e.g., “Is 20 greater than 18?”

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5. Plenary: Consolidating Learning (5 minutes)

Objective: Pupils end the lesson by reflecting on their learning.

• Quickfire Questions:

  • Hold up flashcards (numerals and dots for numbers 15–20). Ask: “What number is this? How do you know?”
  • Point at the number 20 on the class number line. Ask: “What comes before and after 20?”

• Class Reflection: “Tell me one thing you’ve learnt about the number 20 today.”

• End with an exciting number bingo game to review numbers 10–20. Children will mark off numbers as you call them out, ending with a big cheer when “20” is called!

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Assessment Opportunities

• Informal observation during the warm-up and whole-class activities.
• Formative assessment through their representations of 20 with counters and ten frames.
• Check for understanding during quickfire whiteboard practice (e.g., “one more” and “one less” tasks).

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Differentiation

• Support: Pair less confident students with peers. Provide extra visuals and prompts during ten-frame work. Focus on recognising 20.
• Challenge: Encourage confident students to solve word problems involving 20 (e.g., “If you have 20 sweets and eat 2, how many are left?”).

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Homework/Extension Activity

Encourage pupils to go on a “20 hunt” at home. Ask them to find 20 objects to bring or draw for next time (e.g., “20 pebbles,” “20 leaves,” or “20 Lego pieces”). Take turns sharing these finds at the start of the next lesson!

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This lesson is packed with active and visual learning that builds a deep, hands-on understanding of the number 20. It will support Year 1 students in practising place value and solidifying their number knowledge for future progression.