• Quick retrieval from earlier learning (Complete and use a two-set Venn diagram). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. In a club of 47 students, 35 play chess, 20 play the guitar and 7 do neither. How many do both? → 15Prompt: How many do at least one activity?
2. Venn diagram of 31 people: apples only 9, bananas only 10, both 10, neither 2. A person is chosen at random. Find the probability they like apples but not bananas. Give a fraction in its simplest form. → 9/31Prompt: Decide which regions of the diagram you need.
3. In a club of 36 students, 26 play chess, 13 play the guitar and 7 do neither. How many do both? → 10Prompt: How many do at least one activity?

• Take a quick class survey (favorite fruit, travel to school) and ask what the results tell us.
• Share the objective: Use the addition rule P(A or B). Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: P(A) = 0.5, P(B) = 0.5 and P(A and B) = 0.2. Find P(A or B).
• Step 1: 0.5 + 0.5 − 0.2 = 0.8
• Answer: 0.8
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. P(A) = 0.2, P(B) = 0.3 and P(A and B) = 0.1. Find P(A or B). → 0.4Prompt: P(A or B) = P(A) + P(B) − P(A and B).
2. A card is drawn from a standard 52-card deck. Find the probability that it is an ace or a club. Give a fraction in simplest form. → 4/13Prompt: Count each group, then subtract the cards counted twice.

• 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.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. A card is drawn from a standard 52-card deck. Find the probability that it is a red card or a king. Give a fraction in simplest form. → 7/13Prompt: Count each group, then subtract the cards counted twice.
2. In a class, P(plays sport) = 0.7, P(plays an instrument) = 0.5 and P(sport or instrument) = 0.8. Find P(sport and instrument). → 0.4Prompt: Rearrange the addition rule.

Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-10.