Math lesson plan · 7th grade (Year 8 in England) · 45 minutes
Probability that an event does not happen
Statistics and probability
CCSS 7.SP.C.5CCSS 7.SP.C.7England: KS3 ProbabilityEngland: GCSE Foundation Probability
Objective and success criteria
Students will: Probability that an event does not happen.
- 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: Probability of simple events
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 (Probability of simple events). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What is the probability of rolling an even number on a fair six-sided dice? Give a fraction in simplest form. → 1/2Prompt: List all the equally likely outcomes.
- The probability a spinner lands on blue is 0.7. What is the probability it does NOT land on blue? Give a decimal. → 0.3Prompt: An event either happens or it does not: the two probabilities add up to 1 (or 100%).
- What is the probability of rolling a number greater than 4 on a fair six-sided dice? Give a fraction in simplest form. → 1/3Prompt: List all the 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 that an event does not happen. 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: The probability that it rains tomorrow is 0.11. What is the probability that it does NOT rain?
- Step 1: 1 − 0.11 = 0.89
- Answer: 0.89
- 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.
- The probability that it rains tomorrow is 0.52. What is the probability that it does NOT rain? → 0.48Prompt: An event either happens or it does not.
- The probability of winning a game is 7/10. What is the probability of not winning? Give a fraction in simplest form. → 3/10Prompt: Subtract from 1 (which is d/d).
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.
- A bag has 2 red, 6 green and 8 blue marbles. One is picked at random. What is P(not red)? Give a fraction in simplest form. → 7/8Prompt: How many marbles are not red?
- The probability that it rains tomorrow is 0.97. What is the probability that it does NOT rain? → 0.03Prompt: An event either happens or it does not.
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: Probability of simple events.
- 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