Likelihood of Events: Certain, Uncertain, More and Less Likely
Grade 2 probability adds equally likely to the vocabulary, completing the comparative framework. Two events are equally likely when neither has more chance than the other: flipping a fair coin gives equal chances of heads and tails. Connecting probability to data is a new and powerful idea: if 8 out of 10 students prefer summer, the next student surveyed is more likely to prefer summer. Probability is not just about random events: it is about informed prediction from data.
Equally likely events
Two events are equally likely when neither has an advantage. A fair coin: heads and tails are equally likely. A standard die: each face is equally likely. Two bags with the same number of red and blue marbles: equally likely to draw either colour. Establishing this concept requires controlling all variables that could give one outcome an advantage.
Connecting probability to data
If a survey shows that 7 of 10 students prefer apples over bananas, what is more likely: that the next student prefers apples or bananas? Apples: because 7 out of 10 is more likely than 3 out of 10. This connection between data (what happened) and probability (what is likely to happen) is the foundation of statistical inference.
Justifying likelihood with evidence
Good probability reasoning requires evidence. Not just rain is likely but rain is likely because the sky is cloudy, the temperature dropped, and it rained on 4 of the last 5 cloudy days. Evidence-based probability reasoning is a higher-order skill that connects mathematics to scientific and critical thinking.