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9th grade · Math · Unit 1 of 18

Number Sets

Whole, rational and irrational

What your child practices

Natural numbers, whole numbers, integers, rational and irrational numbers, how they fit inside each other, and why there are always more numbers between any two rational numbers.

Alabama Course of Study content standard: GDA.1 · rational and irrational numbers, including square roots

How we explain it

Children can open this short lesson before they practice.

  1. Natural numbers count: 1, 2, 3. Integers add 0 and negatives.
  2. Rational numbers can be written as fractions. Irrational numbers cannot.
  3. Between any two rational numbers there is always another one.

Example: Is 0.25 rational or irrational? 0.25 = 25/100 = 1/4. It is a fraction of whole numbers. Answer: Rational

Number Sets in Alabama

In the Alabama Course of Study, this is unit 1 of 18 in 9th grade Math, before Rearranging Formulas.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Alabama State Department of Education (ALSDE)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which of these sets contains −3?

    • Natural numbers
    • Integers
    • Whole numbers

  2. Question 2

    Which decimal is rational?

    • 0.1010010001… (the pattern never repeats)
    • 0.272727… (the digits 27 repeat)
    • 1.41421356… (never repeats or ends)
    • 3.14159265… (never repeats or ends)

  3. Question 3

    Between 2.1 and 2.2, there is…

    • exactly nine numbers
    • no number
    • an infinite number of rational numbers
    • exactly one number

  4. Question 4

    Which number is rational?

    • √11
    • π
    • −3/8
    • √7

  5. Question 5

    Which number is both a natural number and an integer?

    • 8
    • √8
    • 8/3
    • −8

  6. Question 6

    Which fraction can be written as a terminating decimal?

    • 5/6
    • 7/8
    • 2/9
    • 1/3

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