8.NS.2 
2. Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram, and estimate the value of expressions (e.g., π2 ). For example, by truncating the decimal expansion of √2, show that √2 is between 1 and 2, then between 1.4 and 1.5, and explain how to continue on to get better approximations.
Rational Approximations of Irrational NumbersCopy into your notes.

What is the value of Pi?3.14, there, next question.
Wait, Pi is an irrational number. It cannot be written as a fraction. The decimal expansion of Pi does not terminate, repeat, or repeat in a group. It would seem that we have it wrong in saying that Pi is only 3.14. How can we get away with this atrocity? Do we have to approximate Pi if we want to use it? 
Why must we approximate irrational numbers?While watching the video, listen for how many times we would need to slice the circle in order to completely transform the area into a rectangle. Notice how the slices join together to form what almost looks like a rectangle. Almost.


Truncate  to shorten as by cutting off.
 appearing to terminate abruptly.
 to shorten by dropping one or more digits after the decimal point.
 appearing to terminate abruptly.
 to shorten by dropping one or more digits after the decimal point.
Rational Approximations Lesson and Practice
What two integers is the square root of 34 between?Click on the button when you have the answer.

