Simple Probability

Overview

In this 60-minute lesson, students explore chance using everyday events. They learn to describe outcomes using the language of certain, likely, unlikely and impossible, and they begin to link those words to experiments and observed results.

Learning intentions

• WALT identify practical activities and everyday events that involve chance.
• WALT describe possible outcomes using likely/unlikely and identify some events as certain or impossible.
• WALT make and test predictions by carrying out a short chance experiment and recording results.

Success criteria

• I can sort event cards into certain, likely, unlikely or impossible.
• I can explain why an event is certain/possible using chance vocabulary.
• I can predict what might happen in an experiment and record outcomes using tally marks.

Curriculum links

• Probability — VC2M3P01: students describe events as likely/unlikely and identify events as certain/impossible.
• Probability — VC2M3P02: students conduct repeated chance experiments, record outcomes and recognise variation.

Lesson structure (60 minutes)

1. 0–7 min · Hook: Chance in our day. Teacher displays 4 everyday situation prompts (e.g., “A coin shows heads”, “We draw a blue marker from a bag of blue and red”, “A day without rain in Melbourne tomorrow”, “A die shows 7”). Students turn-and-talk: which ones feel certain, likely, unlikely, or impossible, and why.

2. 7–15 min · Direct teach: Use the vocabulary. Teacher models with a quick think-aloud, defining each word with examples:

• Certain = will happen
• Likely = probably will happen
• Unlikely = probably won’t happen
• Impossible = cannot happen Students practise by holding up fingers for a quick vote on 6 teacher-read scenarios (no long discussion; focus is quick recognition and correct vocabulary).

3. 15–25 min · Guided activity: Sort the event cards. Teacher gives each group a set of cards and a four-column sorting mat (certain/likely/unlikely/impossible). Students discuss in pairs first, then sort as a group. Teacher circulates to listen for chance language and pushes students to justify with reasoning (e.g., “because a die can’t show 7”).

4. 25–40 min · Experiment: Repeated chance trials. Teacher runs a simple, class-friendly experiment: “Bag draw” with 10 small slips labelled (for example) 6 “HAPPY” and 4 “SAD” (or use 5 and 5 for a more balanced option). Students predict the next draw outcome using likely/unlikely language, then complete trials.

• Teacher explains recording: each result gets a tally mark on a class chart.
• Students complete 5 draws per group, then rotate or repeat until class total is clear (aim for at least 20 total trials so variation can be noticed). Teacher prompts: “Was your prediction supported? What surprised you?”

5. 40–50 min · Class discussion: Outcomes and variation. Teacher displays the class tally chart. Students answer:

• Which outcome was more likely?
• Did the results look the same every time? (Lead to “variation” simply: “Some days/rounds it changes.”) Teacher asks students to restate one conclusion using “likely/unlikely” and one event using “certain/impossible” (e.g., “Because we used a die, rolling 7 is impossible.” Connect to VC2M3P01 language.)

6. 50–58 min · Independent practice: Likely/unlikely statements. Students complete a short worksheet page with 8 prompts: write the correct chance word (certain/likely/unlikely/impossible) and add one sentence justification. Prompts include both familiar chance (coin, die) and everyday events (e.g., “This spinner will stop on red” when red is one segment vs half the segments—teacher can predefine spinner in the prompt).

7. 58–60 min · Exit ticket. Students answer one question: “In your experiment, which outcome was more likely, and how do you know using the class results?” (1–2 sentences plus a tally reference.)

Resources

• Event card set (certain/likely/unlikely/impossible) with everyday and game-based scenarios
• Four-column sorting mats (print or on interactive display)
• “Bag draw” materials: opaque bag, labelled slips, table for recording
• Group tally chart (or one large class chart on board)
• Die and/or coin visuals for teacher prompts
• Worksheet: chance word matching + justification
• Exit ticket slips or digital equivalent
• Coloured pencils for sorting and recording

Assessment

• Formative checks during sorting: observe correct placement and listening for use of chance vocabulary with reasoning.
• Formative checks during experiment: check students record outcomes accurately using tallies and attempt predictions before drawing.
• Exit ticket: assess whether students can justify likelihood using either prior knowledge (impossible events) or experiment results (likely/unlikely).

Differentiation

• Support for emerging learners: provide sentence starters
• “I think it is likely/unlikely because…”
• “It is impossible because…”
• “It is certain because…” Also provide a smaller card set (4–6 cards) before the full set.
• Support for students needing structure: give a “reasoning bank” picture cards (die with numbers, coin halves, bag colours) to reference when justifying.
• Extension for students who are ready: ask them to predict the most likely outcome before each run, then compare prediction accuracy across two rounds (“Was it always the same?”).
• For EAL learners: encourage oral rehearsal in pairs before writing, and allow pointing to the class tally chart when justifying likelihood.