Illustrative Mathematics
Irrational Numbers on the Number Line
There are four irrational numbers that participants need to graph. Pi(π), -(½ x π), and √17 are easy to approximate with common rational numbers. On the other hand, the commentary describing the irrational number 2√2 is not...
Illustrative Mathematics
Identifying Rational Numbers
Eight different numbers are listed for mathematics masters to analyze. They simply tell if each number is rational or irrational. They can also explain their reasoning. A simple and straightforward activity that is a handy tool for...
Illustrative Mathematics
Calculating and Rounding Numbers
Mathematicians need to know that not all numbers are rational. We approximate irrational number with rational numbers. That is why a calculator may be misleading. This task give learners an opportunity to see how rounding a number and...
Illustrative Mathematics
Converting Decimal Representations of Rational Numbers to Fraction Representations
A rational number is a ratio of two integers. Discuss with your class how to convert the rational numbers of repeating decimals to fractions. A good commentary on letting x equal the repeating decimal and multiplying each side of...
Illustrative Mathematics
Comparing Rational and Irrational Number
Algebra learners must know how to use rational numbers to approximate irrationals. This resource asks participants to decide which number is larger without using a calculator. It makes a great exercise to use as a five-minute transition...
Education Development Center
Sum of Rational and Irrational is Irrational
Sometimes the indirect path is best. Scholars determine whether the sum of a rational number and an irrational number is irrational. Reading a transcript of a conversation between classmates leads to an indirect proof of this concept.
Illustrative Mathematics
Rational or Irrational?
Is 4 plus the square root of 2 rational or irrational? After your class has gained a basic grasp of rational and irrational numbers, use this worksheet to push them a little further in their understanding. Learners must identify sums and...
Illustrative Mathematics
Placing a Square Root on the Number Line
There are many ways to approach finding the rational approximation of an unknown square root. Here is a problem that will help math learners make a connection between square roots and their order on a number line. As usual, determine two...
Illustrative Mathematics
Calculating the square root of 2
Does a calculator give you the exact value of the square root of 2? Here, learners must decide if 1.414236 is equal to the square root of 2. They must also explain why the square root of 2 could never be equal to a terminating decimal....
5280 Math
Decimal Patterns
Find patterns in the process instead of the result. Learners convert series of decimals and fractions identifying patterns along the way. The lesson includes nine problem tasks with progressively more involved patterns.
Oregon Department of Education
Building Number Sense
It's never too early to begin a child's math education. This collection of fun hands-on activities engage youngsters in building their number sense as they learn how to count objects, identify numerals, compare amounts, and much more.
5280 Math
Pythagorean Triples
From Pythagorean triples to the unit circle. Learners use the Pythagorean Theorem to find Pythagorean triples and then relate their work to the unit circle in a fun algebra project. Their discovery that x^2+y^2 is always equal to one on...
Lawrence Hall of Science
The Math Page: Topics in Pre Calculus: Rational and Irrational Numbers
Here is a site that clearly and thoroughly explains rational and irrational numbers as subsets of the real number system. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point...
Integrated Publishing
Integrated Publishing: Rational and Irrational Numbers
Content, suitable for an introductory algebra course, explains the difference between rational and irrational numbers, how to rationalize the denominator, how to evaluate radicals and the square root process. Practice problems included.
Cut the Knot
What's a Rational Number?
This question is answered by discussing and comparing rational and irrational numbers. For more advanced levels of Algebra, there are sections that discuss different lemmas of rational numbers and give their proofs.
Wolfram Research
Wolfram Math World: Irrational Numbers
This math site explains what it means for a number to be irrational and names various persons who have proven the irrationality of some numbers, the site also gives several numbers who are thought to be irrational yet have not been...
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Rational / Irrational Numbers
Math Forum response providing methods to prove that between any two numbers there exist a rational and an irrational number.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Numbers
Math Forum response to request for information on various number sets. Also defined and discussed are integers, natural numbers, whole numbers, irrational numbers, transcendental numbers, and algebraic numbers.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Definitions of Rational, Irrational
Math Forum definition and explanation of rational and irrational numbers, the definitions of mathematics is also addressed.
Wolfram Research
Wolfram Math World: Rational Number
This site gives an overview of rational numbers, gives interesting facts about the rational numbers including countability and probability of a rational numbers denominator being even. The site also contains related links.
Texas Instruments
Texas Instruments: Real Numbers
Students learn to identify real numbers as rational numbers and irrational numbers. They review rational numbers as repeating decimals, and irrational numbers as non-repeating decimals. They also review commutative, associative,...
J Coffman
Joseph Coffman's Lecture Notes: Properties of Numbers
The lesson examines properties of real numbers. Students learn about rational numbers, properties of real numbers, and irrational numbers. Examples and an assessment are included.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: About Rational Numbers
Math Forum response giving a rather thorough overview of rational and irrational numbers, with a brief look at the history of these and other number sets.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Square Roots and Irrational Numbers
Math Forum response to whether square roots of all non-perfect squares are irrational. Contains a proof showing that such cases are, indeed, irrational.