New
New
Lesson 3 of 14
New
New
- Year 9
The scale of likelihoods
I can show the likelihood of an outcome on a scale.
Lesson details
Key learning points
- A scale can be drawn showing the 5 different likelihoods.
- The likelihood scale can be evaluated to understand why only 5 states are shown.
- Different outcomes for an event can be placed on the likelihood scale.
Keywords
Impossible - An outcome is impossible if there is no possibility that it can happen.
Certain - An outcome is certain if it is guaranteed to happen.
Even chance - An outcome has even chance if its likelihood of happening is the same as its likelihood of not happening.
Common misconception
'Equal chance' means the same as 'even chance'.
When a trial has more than two possible outcomes which are all equally likely to happen, each outcome has less than an even chance of happening. E.g. each number on a dice has the same likelihood of being rolled, but each is less than an even chance.
Present pupils with a spinners, set of cards, dice or other equipment. For each piece of equipment, ask them to come up with some events that are unlikely to happen and some events that are likely to happen. They could then conduct lots of trials with it and see which events occur most often.
Teacher tip
Licence
This content is Β© Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.__________ describes the chance that a particular event will occur.
__________ describes the chance that a particular event will occur.
An event
An outcome
A sample space
A trial
Q2.Which statement is true for this spinner?
Which statement is true for this spinner?
The most likely outcome is for it to land on 'lose'.
The two outcomes are equally likely to happen.
Q3.Which letter is this spinner most likely to land on?
Which letter is this spinner most likely to land on?
a
b
Q4.Select all the multiples of 4.
Select all the multiples of 4.
1
2
Q5.Select all the factors of 4.
Select all the factors of 4.
8
12
Q6.Select all the prime numbers.
Select all the prime numbers.
1
4
Assessment exit quiz
6 Questions
Q1.An outcome is __________ if there is no possibility that it can happen.
An outcome is __________ if there is no possibility that it can happen.
certain
even chance
likely
unlikely
Q2.Which statement describes the meaning of 'even chance'?
Which statement describes the meaning of 'even chance'?
An outcome has less chance of happening than not happening.
An outcome has a greater chance of happening than not happening.
Q3.Match the words with their positions on the scale of likelihoods.
Match the words with their positions on the scale of likelihoods.
Q4.Match each event with the term that describes their likelihood.
Match each event with the term that describes their likelihood.
Q5.A bag contains counters that are each labelled with a letter from A to C. One counter is chosen at random from the bag. Which term describes the likelihood of choosing the letter 'A'?
A bag contains counters that are each labelled with a letter from A to C. One counter is chosen at random from the bag. Which term describes the likelihood of choosing the letter 'A'?
certain
impossible
likely
unlikley
Q6.A regular six-sided dice is rolled. Starting with the least likely, sort the events in increasing order of likelihood.
A regular six-sided dice is rolled. Starting with the least likely, sort the events in increasing order of likelihood.
