Number Intervals: Mapping the Number Line
Big Idea: An interval is a way to describe a continuous set of numbers between two endpoints (or extending infinitely in one direction). Instead of listing individual numbers, intervals let us capture every real number in a range — including decimals and fractions!
Why Do We Need Intervals?
Imagine you're told: "The temperature tomorrow will be between 60°F and 80°F." Does that include exactly 60°F? Exactly 80°F? What about 72.3°F? Interval notation gives us a precise, compact way to answer these questions.