ACARA v9 CONTENT DESCRIPTION “identify practical activities and everyday events involving chance; describe possible outcomes and events as 'likely' or 'unlikely' and identify some events as 'certain' or 'impossible' explaining reasoning”
Long before chance becomes a number, it is a set of words, and Year 3 introduces the four most useful ones. Some things are certain — they will definitely happen, like the sun rising. Some are impossible — they can never happen, like rolling a seven on an ordinary die. In between sit the everyday cases: likely, when something will probably happen, and unlikely, when it probably will not. These words let a child talk about the future sensibly without pretending to know exactly what it holds. This unit builds the chance line, places events on it, and always asks for the reason behind the word.
The chance line
Chance runs from impossible to certain. Tap a word to see what it means.
From impossible on the left to certain on the right, every chance has a place on this line.
From impossible to certain
The four words are not a random list; they sit in order on a line from impossible at one end to certain at the other, with unlikely and likely in between. Picturing chance as a line is the single most helpful idea here, because every event can be placed somewhere along it, and two events can be compared by which sits further toward certain. The line also shows that impossible and certain are the two extremes — nothing is more impossible than impossible — while most of real life lives in the uncertain middle, leaning one way or the other.
Place the event
Read an everyday event and decide where it belongs on the chance line.
Where does this event sit on the chance line: "The sun will rise tomorrow"?
Reading an event for its chance
Placing an event on the line means asking a simple question: must this happen, might it, or can it never? The sun rising must happen, so it goes at certain; rolling a seven on a six-sided die can never happen, so it goes at impossible. Most events sit in between, and deciding whether they lean likely or unlikely is a judgement a child can defend with a reason. This habit — reading a real situation and judging its chance — is the beginning of all probability, and it matters far beyond the classroom, from weather to games to everyday plans.
List the outcomes
Describing chance starts with naming every possible outcome.
Before judging chance, list what could happen with a coin toss.
First, list what could happen
Before judging how likely something is, it helps to list every possible outcome. A coin has two: heads and tails. A six-sided die has six. A three-colour spinner has three. This listing matters because chance is always measured against the full set of possibilities, and a child who can name all the outcomes is ready to reason about any one of them. It also heads off a common confusion: an outcome that is not on the list, like rolling a seven, is exactly what impossible means. Naming the outcomes turns a vague feeling about chance into something a child can point to and count.
The marble bag
The more marbles of a colour, the more likely you pick it. Compare the counts.
No red marbles at all, so picking red is impossible.
More of a thing, more likely
The marble bag connects chance to counting, gently. If a bag holds more red marbles than blue, picking red is likely; if it holds more blue, red is unlikely; if every marble is red, red is certain; and if there are no reds at all, red is impossible. The chance of an outcome depends on how many ways it can happen compared with the rest, and that is the quiet bridge from these words toward the fractions and numbers of later years. For now, comparing the counts is enough: more ways means more likely, fewer ways means less likely.
Could it be fair?
Two outcomes are fair when each is equally likely. Compare their chances.
Are these two chances equally likely (fair) or not?
When chances are equal
A special and important case is when two outcomes are equally likely — a fair chance. A coin is fair because it has one head and one tail; an even or odd roll of a die is fair because three faces are even and three are odd. Recognising fairness, and spotting when something is not fair, is a real-world skill children care about deeply, because games should be fair. The test is always the same: count the ways each outcome can happen, and if the counts match, the chances are equal. A four-to-one spinner is not fair, however much we might wish it were.
Why that word?
Naming a chance is only half the job. Explaining the reasoning is the rest.
Reason 1: because every face is less than 7. Reason 2: because 7 is even. Reason 3: because dice are red.
Always give a reason
The descriptor asks not just for the right word but for the reasoning behind it, and this is what lifts the unit above guessing. Saying a green marble is impossible to pick is only half an answer; the reason — there are no green marbles in the bag — is the mathematics. A good reason always points to the outcomes: how many ways the event can happen, or that it cannot happen at all. Reasons about looks or luck do not count. With the chance words ordered, events placed, outcomes listed, counts compared and fairness judged, a child can describe everyday chance clearly and defend it — and the next Probability unit puts these ideas to the test with repeated experiments.
Quick self-check
1. Which word describes "the sun will rise tomorrow"?
2. Rolling a 7 on an ordinary six-sided die is...
3. A bag holds only blue marbles. Picking a red one is...
4. A bag has 4 red marbles and 1 blue. Picking red is...
5. Which word means an event will definitely happen?