Build Two-Digit Sums

Overview

This 25-minute intervention introduces one child to column addition using two-digit numbers without exchanging. It builds on Year 1 understanding of adding numbers within 20 and place value, while providing a carefully scaffolded early experience of the formal written method required later in Key Stage 2.

Learning intentions

Students will:

• Add two two-digit numbers when the ones total is 9 or less.
• Recognise the tens and ones in a two-digit number.
• Set out numbers correctly in columns.
• Explain that ones are added to ones and tens are added to tens.

Success criteria

• I can identify the tens and ones in a two-digit number.
• I can line up tens and ones correctly.
• I can add the ones, then add the tens.
• I can check whether my answer makes sense.

Curriculum links

• Number — addition and subtraction, Year 1: adding and subtracting numbers within 20, including zero.
• Number — addition and subtraction, Year 2: developing addition of two two-digit numbers.
• Number — addition and subtraction, Year 3: using formal written methods of columnar addition and subtraction with numbers up to three digits.

Lesson structure (25 minutes)

1. 0–4 min · Place-value warm-up. Teacher opens the hook and place-value slides and displays 23 and 14. Ask: “How many tens and how many ones are in each number?” Model separating 23 into 2 tens and 3 ones. Students identify the tens and ones orally and show the quantities with fingers or drawn quick representations.

2. 4–9 min · Model the column method. Teacher uses the worked-example slides to write:

23
+ 14
----

Explain that the ones must be in the ones column and the tens in the tens column. Add the ones first: 3 + 4 = 7. Then add the tens: 2 tens + 1 ten = 3 tens. Reveal 37 and read the calculation aloud. Students help place digit cards or point to each column as the teacher adds.

3. 9–13 min · Guided practice. Teacher gives the child the scaffolded column-addition worksheet and completes the first example together, using the prompts: “Which column do we start with?”, “What is 2 + 5?”, and “How many tens altogether?” Students solve 21 + 15 and 32 + 16, drawing tens and ones beside a calculation if needed.

4. 13–19 min · Independent practice with checking. Teacher refers back to the practice instruction slide and asks the child to complete four calculations on the worksheet: 24 + 13, 35 + 12, 42 + 26 and 53 + 14. Circulate closely, checking alignment before the student calculates. Students add the ones, add the tens, and explain one answer using the sentence frame: “___ ones plus ___ ones equals ___ ones; ___ tens plus ___ tens equals ___ tens.”

5. 19–22 min · Reasoning challenge. Teacher displays two calculations on the error-spotting slide:

24 24
+13 +13
---- ----
37 96

Ask: “Which answer is correct? How do you know?” Students identify that 37 is correct and explain that the digits must be added in their place-value columns. If ready, ask the child to draw tens and ones to prove it.

6. 22–25 min · Review and exit check. Teacher uses the plenary slide and gives the child one final calculation: 31 + 18. Students set it out and solve it independently, then answer: “What must line up?” Teacher records whether the child can align, calculate and explain without prompting.

Resources

• the complete place-value and column-addition slide deck
• the scaffolded column-addition worksheet
• Base-ten blocks, linking cubes or bundles of straws
• Tens-and-ones place-value chart
• Pencil and rubber
• Digit cards, optional
• Mini-whiteboard and pen, optional

Assessment

• During modelling, check whether the child can identify the tens and ones in two-digit numbers and explain why digits must be aligned.
• During worksheet practice, assess accurate column alignment, addition of ones before tens, and whether the child avoids exchanging. Note the level of prompting required.
• Use the final calculation, 31 + 18, as an exit check. A secure response includes correctly aligned columns and the answer 49; if the ones total exceeds 9, stop and reteach rather than introducing exchanging.

Differentiation

• Support with concrete tens and ones, a place-value chart, colour-coded columns and a finger-tracking routine: “ones first, tens next”.
• Keep numbers within 20 initially, such as 12 + ов? Need avoid typo. Use 12 + 6 perhaps, then return to two-digit examples when secure.
• Provide the sentence frame “___ ones + ___ ones = ___ ones” and allow the child to draw or build each number before writing.
• For greater independence, remove the place-value prompts and ask the child to create and solve a similar two-digit addition where the ones total remains 9 or less. Use the Year 1 expectation of addition within 20 as the secure starting point; treat column addition beyond 20 as supported preparation for later statutory learning.