1. …the A, B, C’s of mathematics
The Set of Real Numbers
…the A, B, C’s of mathematics

2. Real numbers Benchmark: Pre-Algebra skill
Objective: I will be able to recognize the special sets of real numbers

3. What is a set? A set is a list of numbers: {3, 7, 15, ¾, π, -10}
We separate the entries with commas, and close off the left and right with { and }.
The empty set is the set containing nothing: { }. It is given the symbol Ø.
Before giving them the answer, check to see if anyone knows. Ask “what does it mean to you?” Ask about the empty set? Ask “what does it mean to you?” Give examples

4. Special sets 1. Natural Numbers: (these are the counting numbers)
2. Whole Numbers: (same as the natural numbers, but include zero)
3. Integers: (same as the whole numbers, but allow negative whole numbers)
Before showing them the sets discuss these 3 sets. Start with the story of numbers. Ask “what does it mean to you?”

5. The set of rational numbers:
Contains:
a. all integers, like -2, 5, or 0
b. all fractions positive and negative, like ¾ and -⅝
c. all decimals that terminate (stop), like .75
d. all decimals that have a repeating block, like …
It is a fact that all rational numbers can be turned into fractions. Ask “what does it mean to you?”

6. The set of Irrational numbers: -
This contains only infinite decimals that don’t have a repeating block.
It is a fact that all roots that don’t come out “cleanly” are irrational.
The most famous irrational number is ….
Examples:
Why R – Q? Because the set of irrationals is not a closed set. Ask “what does it mean to you?”
Give them an example of a decimal and different roots and Ask “what does it mean to you?” by some roots are clean? Ask about the most famous irrational # give hints if needed.

7. So… The set of rational numbers and the set of irrational numbers make up the set of real numbers. Do you think there are numbers that are not real?
Discuss i in passing because it is part of FCAT.