Math lesson plan · 7th grade (Year 8 in England) · 45 minutes
Probability of two independent events
Statistics and probability
CCSS 7.SP.C.8.AEngland: KS3 ProbabilityEngland: GCSE Foundation Probability
Objective and success criteria
Students will: Probability of two independent events.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Compound events and sample spaces; Multiply fractions
Leads to: the next skill in this area.
Materials: Squared paper for charts, Class survey data, Sticky notes for a live chart, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Compound events and sample spaces; Multiply fractions). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Two fair dice are rolled and the scores added. What is the probability the total is 4? Give a fraction in simplest form. → 1/12Prompt: There are 6 × 6 = 36 equally likely outcomes.
- A coin is flipped 3 times. How many outcomes are in the sample space? → 8Prompt: Each flip has 2 outcomes.
- Two fair dice are rolled and the scores added. What is the probability the total is 6? Give a fraction in simplest form. → 5/36Prompt: There are 6 × 6 = 36 equally likely outcomes.
Hook · 5 min
- Take a quick class survey (favorite fruit, travel to school) and ask what the results tell us.
- Share the objective: Probability of two independent events. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: A fair coin is flipped and a fair die is rolled. What is the probability of getting tails and an even number?
- Step 1: 1/2 × 3/6 = 3/12
- Step 2: = 1/4
- Answer: 1/4
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- A fair coin is flipped and a fair die is rolled. What is the probability of getting heads and a multiple of 3? → 1/6Prompt: The coin does not affect the die: the events are independent.
- What is the probability that a coin lands heads 3 times in a row? → 1/8Prompt: Each attempt is independent.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- What is the probability that a coin lands heads 3 times in a row? → 1/8Prompt: Each attempt is independent.
- A fair coin is flipped and a fair die is rolled. What is the probability of getting tails and an even number? → 1/4Prompt: The coin does not affect the die: the events are independent.
Watch out for
- Forgetting to put data in order before finding the median.
- Reading a bar's height wrongly when the scale goes up in 2s or 5s.
Support and stretch
Support
- Review first: Compound events and sample spaces.
- Use concrete materials: squared paper for charts.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-7.
Free lesson plan from eurekami.com/lesson-plan-builder