Chance Basics

Overview

This lesson introduces probability as a way to describe likelihood in everyday situations, using “chance” language and the idea of a scale from 0 to 1. It builds towards later lessons where students record outcomes and calculate theoretical and experimental probabilities.

Learning intentions

Students will:

• Understand and use basic probability terms such as outcome, event, possible, impossible, and equally likely.
• Describe likelihood using appropriate language (e.g., “more likely”, “less likely”, “certain”, “unlikely”).
• Begin to connect probability to the 0–1 probability scale conceptually.
• Identify probability scenarios from short descriptions and say what outcomes/events mean.

Success criteria

Students can:

• Define at least three probability terms correctly in context.
• State whether an outcome is certain, likely, unlikely, impossible, or has an overall higher/lower chance.
• Recognise an event as a collection of one or more outcomes.
• Give a reasonable probability statement (using chance language) for a given scenario.

Curriculum links

• Record, describe and analyse frequency of outcomes in simple probability experiments involving randomness and fairness, using appropriate language and the 0–1 probability scale.
• Generate theoretical sample spaces for single events with equally likely outcomes and calculate theoretical probabilities (introduced conceptually through “equally likely”).
• Understand that the probabilities of all possible outcomes sum to 1 (first encountered as a “complete set of outcomes” idea).
• Enumerate sets and unions/intersections systematically using tables/grids (used today through simple outcome tables for scenarios).

Lesson structure (60 minutes)

1. 0–8 min · Do Now (Likelihood check). Teacher displays 5 short scenarios; students answer individually in silence, then mark using an answer slide for quick self-check. (Examples: “A fair coin shows heads” / “Picking a red marble when none are red” / “Spinning a number less than 3 on a die.”)

2. 8–18 min · I Do (Probability meaning). Teacher models thinking with a visual probability line from 0 (impossible) to 1 (certain), and uses real-life examples (weather, games, cards). Students follow along with a labelled diagram: outcomes → event → likelihood statement.

3. 18–28 min · We Do (Daily chance discussion). Teacher leads a whole-class discussion using 3 prompts (“Which is more likely?” “What outcomes could happen?” “What would make it certain or impossible?”). Students turn and talk for 30–40 seconds at two points, then share a class answer and one piece of reasoning.

4. 28–38 min · We Do (Outcomes and events, whole class table). Teacher uses one scenario (e.g., “Choose 1 toy from a box with 2 red, 1 blue” or “Spin a spinner labelled 1–4”). Students help complete a simple outcomes list, then identify an event such as “red” or “an even number” and decide if it is more/less likely.

5. 38–55 min · You Do (Identify probability scenarios). Students work independently on a worksheet with 6 descriptions; for each, they:

• list possible outcomes (or state “no possible outcomes” if impossible),
• name an event using probability language,
• write a likelihood statement (certain/likely/unlikely/impossible or “more likely/less likely”). Teacher circulates, using quick prompts: “What outcomes are possible?” “Which outcomes belong to your event?”

6. 55–60 min · Exit ticket (Quick success check). Students answer two questions:

• “Give one example of an outcome and one event from a scenario we used.”
• “Is the event ‘impossible’ ever possible? Explain with one word.” Teacher collects or checks live for common misconceptions.

Resources

• Do Now question sheet (5 short likelihood items) and answer slide
• Visual probability scale diagram (0 to 1 with labels: impossible → certain)
• Scenario cards or projected examples (coin, die/spinner, coloured objects)
• Worksheet for “You Do” (6 scenario prompts with outcome/event space)
• Student notebooks, pens/pencils
• Dyslexia-friendly reading pack (short sentences, larger font option)
• Sentence starter strips (e.g., “An outcome is…”, “An event is…”, “This is likely because…”)

Assessment

• Formative checks during Do Now self-marking (look for misconceptions about “impossible” and “certain”).
• During We Do, listen for correct use of “outcome” vs “event” and ability to give a reason.
• You Do worksheet: teacher notes on whether students can list outcomes and express events using chance language.
• Exit ticket: checks vocabulary accuracy and the 0/1 idea through “impossible/certain” link.

Differentiation

• Support: dyslexia-friendly reading options (larger font, fewer words per line), sentence starters, and a pre-filled probability scale for reference.
• Support: for students needing extra help, provide a partially completed outcomes table template (two columns: “Outcome” / “In the event?”).
• Challenge (advanced learners): add an extra prompt: “Is the event more likely than its complement? Prove it by listing outcomes.”
• Scaffold for diverse learners: model one example fully before independent work; allow students to answer “event” using pictures/boxes if they struggle with wording.
• EAL: encourage use of word banks (“possible outcomes”, “certain”, “impossible”, “more likely”, “less likely”) and accept brief explanations using structured starters.