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9th grade · Math · Unit 6 of 17

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.

Alaska content standards learning standard: N-RN.3 · comparing rational and irrational numbers

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 Alaska

In the Alaska content standards, this is unit 6 of 17 in 9th grade Math, after Statistics in Society and before Expressions.

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: Alaska Department of Education and Early Development

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 number is an integer?

    • −5
    • 0.5
    • √5
    • −5/2

  2. Question 2

    Which statement is true?

    • Every rational number is an integer
    • Every integer is a rational number
    • Every irrational number is a rational number
    • No integer is a rational number

  3. Question 3

    Which number is irrational?

    • 1.7
    • √3
    • 7/4
    • −1.75

  4. Question 4

    Which decimal is rational?

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

  5. Question 5

    Which of these sets contains −3?

    • Whole numbers
    • Natural numbers
    • Integers

  6. Question 6

    Which number is irrational?

    • −2/9
    • 0.125
    • √10
    • √25

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