True or False Facts

Overview

This is lesson 2 of 5 in Number Sentences Make Sense. Students use one-digit addition and subtraction facts to decide whether both sides of a number sentence are equal, then justify their thinking with counters, drawings, or equations. The lesson builds on prior work with number bonds and fact families.

Learning intentions

• WALT check whether addition and subtraction number sentences with one-digit numbers are true or false.
• WALT calculate both sides of an equation.
• WALT represent and explain our mathematical thinking.
• WALT listen to and compare different strategies.

Success criteria

• I can calculate both sides of a number sentence.
• I can decide whether the sentence is true or false.
• I can use counters, a drawing, or an equation to show my thinking.
• I can explain why my answer is true or false.

Curriculum links

• Number: use addition and subtraction facts within 20 and connect related facts.
• Algebraic thinking: recognise that the equals sign means “has the same value as”, not “the answer comes next”.
• Mathematical practices: represent, reason, communicate, and justify mathematical ideas.
• Mathsteasers: use challenging questions to deepen understanding and encourage higher-order thinking.

Lesson structure (60 minutes)

1. 0–10 min · Fluency warm-up. Display the warm-up questions in the fluency warm-up slides. Teacher revisits quick addition and subtraction facts within 10, including fact families such as 3 + 4, 4 + 3, 7 − 3 and 7 − 4; students respond with fingers, mini-whiteboards, or partner talk. Pause to ask, “How did you know?” rather than focusing only on speed.

2. 10–25 min · Teacher modelling. Open the introduction and modelling slides and introduce the words true, false, equal, left side and right side. Model 7 − 5 = 6 − 4 by building both sides with counters, recording 2 = 2, and saying, “Both sides have the same value, so this sentence is true.” Model a false example, such as 8 − 3 = 4 + 2, calculating each side separately and explaining that 5 is not the same as 6. Emphasise that the equals sign compares the two sides. Students rehearse the sentence frame: “The ___ side equals ___. The ___ side equals ___. They are/are not equal, so the sentence is true/false.”

3. 25–32 min · Guided practice. Give pairs counters and the Twenty-frame Mats. Teacher displays three sentences from the guided practice slides, one at a time, such as 5 + 2 = 9 − 2 and 4 + 4 = 10 − 2. Students build or draw each side, calculate, and show thumbs up for true or thumbs down for false. Select students to explain different representations, checking that they compare both sides rather than stopping after the first calculation.

4. 32–50 min · True-or-false sorting game. Distribute the true-or-false sorting and justification sheet and provide each pair with teacher-prepared number-sentence cards. Students sort the cards into TRUE and FALSE, then choose at least four sentences to justify on the worksheet using counters, drawings, or equations. Include balanced examples with addition on both sides, subtraction on both sides, and mixed operations, for example 3 + 5 = 10 − 2, 9 − 6 = 2 + 1, and 6 + 1 = 8 − 3. Partners take turns as “calculator” and “checker”: the calculator works out both sides and the checker asks, “How can you prove it?” Teacher circulates, asks “What does the equals sign tell us?” and records students needing further support.

5. 50–55 min · Share and discuss. Return to the sorting discussion slides. Invite pairs to defend one true and one false sentence. Compare a counter model, a drawing, and an equation, highlighting that different representations can prove the same result. Address the misconception that a number sentence is true whenever the calculation on the left is correct.

6. 55–60 min · Exit check. Display the exit questions on the plenary and exit-check slides. Students independently complete the final section of the individual exit-check questions: decide whether 7 − 2 = 3 + 2 is true or false, show how they know, and complete 4 + 3 = 10 − __. Collect responses as students leave and briefly ask selected students to explain their reasoning.

Resources

• the complete lesson slide deck
• the true-or-false sorting and justification sheet
• the Twenty-frame Mats
• Teacher-prepared true-or-false number-sentence cards
• Two-colour counters or linking cubes
• Mini-whiteboards and pens
• Pencils and crayons
• Board or display screen

Assessment

• Listen during the warm-up and guided practice for accurate fact recall and correct interpretation of the equals sign.
• Observe pair sorting and questioning, noting whether students calculate both sides and justify their decisions.
• Use the independent exit check to identify students who need more work with subtraction, equality, or explaining their reasoning before lesson 3.

Differentiation

• Support learners with counters, the Twenty-frame Mats, worked examples, oral rehearsal, and a reduced number range using facts within 5. Provide the sentence frame: “The left side is __. The right side is __. The sentence is __ because __.”
• Pair learners strategically so that partners can model language and checking routines without one student doing all the calculating. Read sentences aloud and use colour to distinguish the two sides.
• For learners who need an additional scaffold, provide cards with one side already represented pictorially and allow them to explain orally before recording.
• Extend advanced learners by asking them to write false sentences that look convincing, then change one number to make each sentence true. Challenge them to find more than one change and explain why it works.