Building Fraction Sums

Overview

This is lesson 6 of 10 in Understanding Fractions Together. Students use fraction strips and visual models to add simple fractions with different denominators, focusing on finding equivalent fractions before adding. Examples are limited to friendly denominators such as 2, 4 and 8, with digital fraction-calculator support available.

Learning intentions

• WALT add fractions with different denominators.
• Students will identify a common denominator using a fraction model.
• Students will rename fractions as equivalent fractions.
• Students will add fractions and explain their thinking using pictures, words or numbers.

Success criteria

• I can find a common denominator for two fractions.
• I can rename one or both fractions as equivalent fractions.
• I can add the numerators while keeping the denominator the same.
• I can check my answer with a model or fraction calculator.

Curriculum links

• Recognising and representing unit fractions and common fractions using diagrams and materials.
• Recognising equivalent fractions and explaining that they name the same amount.
• Solving simple addition problems involving fractions with related denominators.
• Communicating mathematical thinking using representations, symbols and digital tools.

Lesson structure (45 minutes)

1. 0–5 minutes – Welcome and hook Open with the fraction-sharing hook. Show two quarter pieces and one half piece and ask: “How much pizza is this altogether?” Invite students to make a prediction without calculating. Explain that today’s fractions may have different denominators, but the pieces must be changed to the same size before adding.

2. 5–12 minutes – Connect to known fractions Revisit numerator and denominator using a large visual model on the slides. Ask students to show one-half, one-quarter and one-eighth with fingers, drawings or the fraction materials. Emphasise that the denominator tells the size of the pieces and that pieces must be the same size to be combined fairly.

3. 12–22 minutes – Teacher modelling Display the worked example on the common-denominator modelling slides: 1/2 + 1/4 =? Build the fractions using the fraction wall and strip cards. Show that 1/2 is the same as 2/4, then combine 2/4 + 1/4 = 3/4. Repeat with 1/4 + 2/8, showing that 1/4 = 2/8, so the answer is 4/8 or 1/2. Use the language: “Find the common denominator, rename, add, simplify if we can.”

4. 22–34 minutes – Supported partner practice Place students in five pairs, with one student working as the explainer and one as the builder; the eleventh student works with the teacher or a peer model. Distribute the fraction addition practice sheet. Students use the fraction strips to solve examples such as 1/2 + 1/4, 1/4 + 1/8, 2/4 + 1/8 and 1/2 + 2/8. For each question, students draw or build the fractions, write the equivalent fraction, then add. Pause halfway for a quick whole-class check.

5. 34–40 minutes – Independent choice and digital checking Students complete two selected worksheet questions independently. They may use a device with the digital-checking instruction slide to access the fraction calculator tool after recording their own answer. Students compare the calculator result with their model and circle “matches” or “I need to check”. The teacher conferences with students who are still confusing numerators and denominators.

6. 40–45 minutes – Plenary and exit response Return to the review and exit-question slides. Ask: “Why can’t we add 1/2 + 1/4 by adding the denominators?” Students respond verbally, with a drawing or on the back of the worksheet. Invite two students to explain how 1/2 becomes 2/4. Collect responses to identify the next teaching focus.

Resources

• the fraction addition teaching deck
• the fraction addition practice sheet
• the fraction wall and strip cards
• Fraction calculator tool on classroom devices
• Whiteboard and markers
• Pencils, coloured pencils and erasers
• Optional enlarged fraction models for teacher demonstration
• One device per pair where available

Assessment

• Observe whether students select a common denominator and accurately rename fractions during modelling and partner work.
• Check worksheet representations, equivalent fractions and final sums; look for the common error of adding denominators.
• Use the plenary explanation and calculator-check record to group students for the next lesson.

Differentiation

• Support: begin with denominators 2 and 4 only; provide pre-selected fraction strips, enlarged models and a four-step prompt: build, rename, add, check.
• Support: allow students to answer through drawing, pointing, speaking or using sentence frames such as “___ is the same as ___ because…”.
• Digital assistance: permit the fraction calculator after students attempt each question, using it as a checking tool rather than a replacement for modelling.
• Extension: students solve a related problem using denominators 4 and 8, write two equivalent forms of the answer and explain why both forms are correct.
• EAL/SEN: explicitly teach numerator, denominator, equal and common; use colour coding, repeated modelling, reduced written load, peer support and frequent movement between concrete materials and symbols.