ACARA v9 CONTENT DESCRIPTION “list the possible outcomes of chance experiments involving equally likely outcomes and compare to those which are not equally likely”
Builds on earlier chance language, where events were called possible, likely or impossible. Year 5 makes that sharper by looking closely at the outcomes themselves: listing every possible outcome of an experiment, and deciding whether those outcomes are equally likely or not. Some experiments, like a fair coin or an ordinary die, treat every outcome the same; others, like a loaded spinner or a bag with more of one colour, do not. Telling these two kinds of experiment apart, and comparing them, is the heart of Year 5 chance, and it prepares the way for measuring probability in later years.
Listing the possible outcomes
Every chance experiment has a set of possible outcomes, and the first step is to list them all. Tossing a coin has two outcomes, heads and tails; rolling an ordinary die has six, the numbers one to six; spinning a four-colour spinner has four. Listing the outcomes carefully, without missing or repeating any, is what makes the rest of the reasoning reliable. Once the full list is written down, the number of possible outcomes is simply how many are in it, and every question about the experiment starts from this list.
Listing the possible outcomes
Write down every outcome, none missed or repeated.
Listing every outcome carefully is what makes the rest of the chance reasoning reliable.
When outcomes are equally likely
Outcomes are equally likely when each one has the same chance of happening. A fair coin, an ordinary die and a spinner divided into equal sections all give equally likely outcomes, because the experiment treats no outcome differently from another. Heads is as likely as tails, and every face of a fair die has the same chance. Recognising equally likely outcomes matters because these are the experiments where each outcome can be treated the same, and where chance feels perfectly balanced. The test is simple: is there any reason one outcome should come up more often than another? If not, the outcomes are equally likely.
When outcomes are equally likely
Equally likely means no outcome is favoured.
Are the outcomes from a fair coin equally likely?
When outcomes are not equally likely
Many experiments do not have equally likely outcomes. A spinner with one large section and several small ones can land on any of its colours, but the large section comes up far more often. A bag holding four red counters and one blue counter can give red or blue, but red is much more likely to be drawn. A drawing pin can land point-up or point-down, but one way is usually easier than the other. In all of these the list of outcomes is still clear, yet the outcomes are not balanced, so they are not equally likely. Spotting why an experiment is uneven is just as important as spotting when it is fair.
When outcomes are not equally likely
Some experiments favour one outcome over another.
Are the outcomes of a fair die equally likely or not?
Which outcome is more likely
When outcomes are not equally likely, it makes sense to ask which one is more likely. The answer comes from looking at how many ways, or how much room, each outcome has. In a bag of four red and one blue counter, there are more red counters, so red is more likely to be drawn. On a spinner, the colour with the largest area is the one the arrow is most likely to stop on. Comparing outcomes this way, by counting or by area, replaces guessing with a clear reason, and it shows that more likely simply means there are more chances for that outcome to happen.
Which outcome is more likely
More ways to happen means more likely.
The outcome with more ways to happen is the more likely one.
Comparing the two kinds of experiment
Putting it all together means comparing experiments and sorting them into two kinds. Given any experiment, the question is whether its outcomes are equally likely or not. A fair coin, an ordinary die and an equal spinner go in the equally likely group; a loaded spinner, an uneven bag and a drawing pin go in the other. Making this comparison sharpens the idea of chance: it shows that listing outcomes is only the start, and that what really matters is whether those outcomes share the chance equally. The same experiment can often be made fair or unfair by changing how it is set up.
Comparing the two kinds of experiment
Sort each experiment as fair or not.
Reveal whether each experiment has equally likely outcomes.
Describing chance with care
Describing chance well in Year 5 means doing each step with care: list every possible outcome, decide whether those outcomes are equally likely, and, when they are not, work out which outcome is more likely and why. Comparing fair experiments with unfair ones builds a clear, honest sense of how chance works, without yet putting a number on it. With these habits a child can look at any coin, die, spinner or bag and describe its outcomes accurately, ready for the measuring of probability that later years bring.
Quick self-check
1. When you roll a fair six-sided die, how many possible outcomes are there?
2. Outcomes are equally likely when...
3. A bag holds 4 red counters and 1 blue counter. Drawing one gives outcomes that are...
4. In that bag (4 red, 1 blue), which colour is more likely to be drawn?
5. Which has equally likely outcomes: a fair coin, or a spinner with one big and several small sections?