Adding Larger Numbers

Overview

Unit: Adding Up Adventures (Lesson 5 of 6)
Duration: 60 minutes
Class size: 25 students
Age Group: KS1 and early KS2 (aged 6 to 8)
National Curriculum Focus:
- Mathematics Programmes of Study: Number – Addition and Subtraction
- For KS1 (Years 2 and 3), focus on understanding addition facts and extending addition strategies to 2-digit numbers.
- Relevant NC references:
  - Year 2: "Add and subtract numbers mentally, including: a two-digit number and ones, a two-digit number and tens."
  - Year 3: "Add numbers with up to three digits, using formal written methods of columnar addition."

Learning Objectives

By the end of this lesson, pupils will be able to:

Confidently add two-digit numbers by breaking them into tens and ones (NC Year 2 number addition objective).
Use a number line to visualise and perform addition of two-digit numbers by counting in steps (Year 2 NC - practical strategies).
Use base ten blocks (Dienes resources) to concretely represent addition problems and combine tens and ones (Year 2 NC - use of physical resources to support understanding).
Explain their method of addition to a partner or the class, using appropriate mathematical language such as “tens,” “ones,” “jump,” and “partition.”
Develop mental strategies for adding large two-digit numbers, building towards the formal methods in Year 3.

Key Vocabulary

Tens
Ones (Units)
Number line
Partition
Add / sum / total
Jump (on the number line)
Base ten blocks / Dienes blocks

Resources Needed

Large classroom number line (0–150) visible to all pupils
Individual number lines printed for students (0–100)
Base ten block sets for pairs (tens rods and unit cubes)
Whiteboards and pens
Worksheet with addition problems of two-digit numbers (differentiated)
Visual cards showing partitioned numbers (e.g., 47 as 40 + 7)
Interactive counting app or visualiser (optional)

Lesson Breakdown

Starter (10 minutes)

Objective: Activate prior knowledge on addition, focusing on mental strategies for single-digit and two-digit numbers.

Begin with a fun oral quick-fire addition quiz:
- Add 9 + 6, then add 15 + 4, then 24 + 10, etc.
- Encourage pupils to "think aloud" how they work out answers.
Introduce breaking down numbers (partitioning) to prepare for large numbers. For example:
“24 + 17 can be thought of as 24 + 10 + 7.”
Show base ten blocks for reminder and quick revision: How many tens and ones are in 24? 17?

Main Activity 1: Number line jumps (20 minutes)

Objective: Use vertical or horizontal number lines to add larger numbers by counting in tens then ones.

Display a large number line on the board from 0 to 150.
Pose a problem: 46 + 25. Demonstrate:
- Start at 46.
- First, jump 20 steps forward (arriving at 66).
- Then jump 5 more steps (arriving at 71).
Hand out number lines to pupils.
Give pairs of pupils similar problems (e.g., 53 + 32, 68 + 14).
Pupils take turns “jumping” on their number lines with finger or marker, verbalising their jumps.
As pupils work, circulate and prompt with questions such as:
- “How did you split 25?”
- “What number did you land on after jumping 10?”
- “Can you count the jumps in a different way?”

Main Activity 2: Base ten block addition (15 minutes)

Objective: Use concrete equipment to model and combine two-digit numbers.

Recap that numbers can be split into tens and ones using base ten blocks.
Model addition with base ten blocks, e.g. 37 + 46:
- Show 3 tens rods + 7 unit cubes + 4 tens rods + 6 unit cubes.
Demonstrate how to combine the tens first, then the ones.
If the ones add up to more than 10, model exchanging (e.g., 7 + 6 = 13: 10 units change to one ten rod).
Pupils work in pairs to use their base ten blocks to solve new addition problems from the worksheet.
Encourage pupils to draw their base ten model on whiteboards after the physical manipulation.
Ensure pupils verbalise their thinking, e.g. “Three tens plus four tens equals seven tens..."

Plenary (10 minutes)

Objective: Consolidate learning and assess understanding.

Gather pupils for a quick class discussion.
Ask volunteers to demonstrate one addition problem on the number line and one using base ten blocks.
Pose reflective questions:
- “Which method helped you the most?”
- “Why is it easier to break down numbers when adding?”
Provide a mixed addition problem (e.g. 55 + 28) on the board and ask pupils to:
- Solve mentally if confident
- Or use the number line or base ten blocks
Finish with a short exit ticket: On a mini whiteboard, pupils write the answer to:
“42 + 37 = ?”
Collect these for formative assessment.

Assessment and Differentiation

Assessment for learning:

Teacher observations during paired activities focusing on correct use of partitioning and number line jumps.
Exit tickets to quickly evaluate understanding.
Pupil explanations of methods used verbally or written.

Differentiation:

Support: Provide pre-partitioned number cards and scaffolded questions; use base ten blocks for tactile learners.
Challenge: Ask higher attaining pupils to try three-step jumps (e.g., first 10, then 10, then units) or begin looking at adding three 2-digit numbers mentally.
Use questioning to deepen understanding or extend thinking for rapid learners.

Cross-Curricular Links and Enrichment

English: Encourage use of precise mathematical language during discussions.
ICT: Optional use of interactive number line apps to visualise number jumps.
PSHE: Collaborative work on paired tasks promotes teamwork and communication skills.

Reflection and Next Steps

Reflect on effectiveness of concrete to pictorial approaches bridging to abstract thinking.
Next lesson (Lesson 6): Introduce written column addition for two-digit numbers using the concrete and visual knowledge gained today as foundation.

Thank you for reviewing this plan. This approach integrates hands-on learning, visual aids, mental strategies, and formative assessment directly aligned to the National Curriculum standards for Year 2 and supports transition into Year 3 objectives.

Teaching Instructions