Basics of Probability
Lessons in this chapter
About Basics of Probability
Chance is a single lesson that extends 1st grade’s three categories into a fuller vocabulary of likelihood.
Use the Language of Chance adds words between the extremes. 1st grade sorted events as possible, impossible or certain; here likely and unlikely fill the large middle, so a child can say that rain tomorrow is likely rather than merely possible.
The value is in the comparison. Being able to say one outcome is more likely than another is an ordering, and ordering outcomes by likelihood is what probability does once numbers are attached in middle school.
No fractions or percentages appear, and that is deliberate. What 2nd grade is building is the habit of reasoning about which outcomes are available and how often each would happen, which is the thinking the arithmetic later formalises.
Use the Language of Chance is the chapter's only lesson, and it opens as a worksheet in the page with each question marked as your child answers it. The work is sorting everyday events as certain, likely, unlikely or impossible, and then giving a reason for the sort. It is free and takes a single sitting.
Frequently asked questions
Describing how likely an event is using words: certain, likely, unlikely and impossible, with no numbers or fractions involved. Probability is not part of the U.S. Common Core at 2nd grade at all, so this chapter does not map onto one of the 2nd grade domains. It is taught here because ordering outcomes by likelihood is the reasoning that formal probability later attaches numbers to.
Describing how likely an event is using words: certain, likely, unlikely and impossible. No numbers or fractions are involved yet.
1st grade used three categories, possible, impossible and certain. This adds likely and unlikely, which fill the middle and let kids compare two possible events.
Because putting outcomes in order of likelihood is what probability does. Attaching numbers to that order is all that changes in later grades.
Something that usually happens but is not guaranteed: the school bus arriving on time, or a coin landing heads at least once in ten flips.
Because the reasoning comes first. A child who can argue about which outcomes are available is ready for fractions of outcomes later; one who learns the arithmetic first often cannot say what it means.