Chance Outcomes

Overview

Students explore probability through everyday events and chance experiments, comparing likelihood and ordering outcomes by chance. They also learn to recognise when events are independent or dependent, using repeated trials to support their thinking.

Learning intentions

• Students will describe possible outcomes of a simple chance experiment using everyday language.
• Students will order events or outcomes from least likely to most likely.
• Students will explain how evidence from repeated trials can change or strengthen predictions.
• Students will identify whether two events are independent or dependent (linked).

Success criteria

• I can list possible outcomes for a chance experiment and describe what might happen.
• I can order outcomes/events from least likely to most likely and justify my reasoning.
• I can record results from repeated trials and comment on how results vary.
• I can explain whether one event affects the other (independent vs dependent).

Curriculum links

• Probability — students describe possible everyday events and possible outcomes, order outcomes by likelihood, and identify independent or dependent events.
• Probability — students conduct repeated chance experiments to observe relationships and identify variation in results.
• Mathematics reasoning — students use evidence from trials to support claims about likelihood.

Lesson structure (50 minutes)

1. 0–5 min · Hook (quick think). Teacher shows the introduction slides with a scenario: “At lunch you can win either a jam or chocolate snack. Which is more likely: getting jam or getting chocolate?” Students think-pair-share, then write one prediction and one reason.

2. 5–12 min · Direct teaching (likelihood language). Teacher uses the introduction slides to model: possible outcomes, then “least likely” to “most likely” ordering, using “always / sometimes / never” language. Students repeat the model with the snack example and add a second prediction (e.g., “jam twice as likely” if a condition is stated).

3. 12–18 min · Mini-demonstration (independent vs dependent idea). Teacher shows the introduction slides with two short event pairs:

• Pair A (independent): “Coin toss 1 is heads, coin toss 2 is heads.”
• Pair B (dependent): “Pick a red counter, then pick another counter without replacing it.” Teacher asks: “Does what happens first change what can happen second?” Students hold up fingers (0–2) for “independent” or “dependent”, then justify using one sentence.

4. 18–32 min · Main investigation (repeated trials). Teacher explains the experiment using the introduction slides and then distributes the probability trials worksheet to pairs. Experiment: Use a spinner with 3 equal sections (A, B, C) OR use a die where outcomes are grouped (e.g., 1–2 = A, 3–4 = B, 5–6 = C). Students run 30 spins/rolls, record outcomes in a tally chart, and answer:

• “What outcomes happened?”
• “Which is least likely / most likely based on your results?”
• “How much variation do you notice from trial to trial (first 10 vs last 10)?” Teacher circulates, prompting evidence (“Show me your tallies”) and vocabulary (“possible outcomes”, “likelihood”, “variation”).

5. 32–41 min · Ordering and reasoning (link to likelihood). Teacher brings class back to the introduction slides and displays a set of example event statements (e.g., “Rolling an even number”, “Rolling a number greater than 4”, “Spinning A after B”). Students complete a whole-class ordering by discussing which statements are more or less likely and why. Teacher checks: “Are we ordering based on theory (equal sections) or on our data (our trial results)?” Students vote and justify using one piece of recorded evidence.

6. 41–47 min · Dependent event challenge (no replacement). Teacher uses the introduction slides to pose one question: “If you pick one counter from a bag, then you pick again without replacing, are the events dependent?” Students answer in notebooks, then share with a partner using a cause phrase: “Because the first pick changes…”.

7. 47–50 min · Plenary and exit check. Teacher uses the introduction slides to show an “exit ticket” prompt: “Order these from least to most likely: (1) A, (2) B, (3) C from your experiment; then state whether two picks are independent or dependent and explain in one sentence.” Students write brief answers on the back of the probability trials worksheet and submit.

Resources

• the introduction slides
• the probability trials worksheet
• Spinners (equal sections) or dice (grouped outcomes) and clipboards/tally sheets
• Counters (at least one bag per group) for dependent event example
• Timer for 30 trials and classroom display board for collective tally
• Student pencils and erasers
• Access to digital timer/stopwatch (optional)

Assessment

• Teacher observation during trial recording: correct use of “possible outcomes” and tallying consistently.
• Checks for reasoning: during ordering discussions, listen for justifications grounded in outcomes and evidence.
• Exit check (final 3 minutes): students order likelihood and correctly identify independent vs dependent with a brief explanation.

Differentiation

• Support: Provide sentence starters on the probability trials worksheet (e.g., “Least likely because…”, “The events are dependent because…”).
• Support: Group students strategically so pairs include at least one confident recorder; teacher prompts with guiding questions.
• Extension: Challenge students to predict what would happen if the number of trials increased (e.g., “Which outcome might gain/lose tallies?”) and to compare early vs late results.
• EAL/SEN: Keep event wording consistent; model once with the class before releasing pairs to experiment; allow verbal responses before written on the worksheet.