Data & Chance
Understanding Chance: Impossible, Unlikely, Likely, Certain
3rd Class · 4th Class · 5th Class · 6th Class
- ✓By the end of this lesson students will be able to identify events as impossible, unlikely, likely, or certain.
- ✓By the end of this lesson students will be able to use appropriate language to describe the chance of an event happening.
- ✓By the end of this lesson students will be able to give examples of events that are impossible, unlikely, likely, or certain.
- ✓By the end of this lesson students will be able to understand that chance helps us talk about how often things might happen.
Key concepts
Chance tells us how likely it is that something will happen. We use words like 'impossible', 'unlikely', 'likely', and 'certain' to describe chance.
An impossible event is something that can never, ever happen. There is no chance of it happening. For example, a fish flying in the sky.
An unlikely event is something that probably won't happen, but it's not impossible. It has a small chance of happening. For example, winning a big prize in a raffle.
A likely event is something that probably will happen. It has a good chance of happening. For example, it raining in Ireland next week.
A certain event is something that will definitely happen. It is sure to happen. For example, the sun will rise tomorrow morning.
Key facts to remember
- 1Chance helps us predict if something will happen.
- 2Impossible means it will never happen.
- 3Unlikely means it probably won't happen, but it could.
- 4Likely means it probably will happen.
- 5Certain means it will definitely happen.
- 6We use these words to describe how often events might occur.
Worked examples
Example 1
For each event, say if it is Impossible, Unlikely, Likely, or Certain:
Answer
a) Impossible b) Certain c) Unlikely d) Likely
Think about whether the event can happen at all, and if so, how often it usually happens.
Example 2
A bag contains 3 red balls and 1 blue ball. If you pick one ball without looking, what is the chance of picking:
Answer
a) Likely b) Impossible c) Unlikely
Count the number of each item to help you decide the chance.
Example 3
Think about the weather in Ireland. Describe the chance of these events using 'Impossible', 'Unlikely', 'Likely', or 'Certain':
Answer
a) Likely b) Unlikely c) Impossible
Use your knowledge of real-world events to help you decide.
Common mistakes
- ✗Confusing 'unlikely' with 'impossible' (e.g., thinking an unlikely event can never happen).
- ✗Confusing 'likely' with 'certain' (e.g., thinking a likely event will always happen).
- ✗Not considering all possible outcomes when deciding the chance of an event.
- ✗Using words like 'maybe' or 'sometimes' instead of the specific chance words (impossible, unlikely, likely, certain).
Exam tips
- ★Read the question carefully to understand exactly what event you need to describe.
- ★Think about all the possible things that could happen in the situation.
- ★Choose the most accurate word from 'impossible', 'unlikely', 'likely', or 'certain'.
- ★If asked, explain your reasoning clearly using simple language.
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