Fractions as Functions First Group FFF Group

Introduce fractions as functions first. So 1/2 is defined as a function whose domain is even numbers.  This is before defining rational numbers.

When going to rational numbers, downplay the equivalence class part.  A rational representative or rational number representative is a pair p/q and we have rules.  That some of these are equivalent can be stated, but not in the same sentence.

Rational reps are a pair p/q, as long as q is not zero.  What rational number does a rep represent?  This is the next question and the student is led to ask it. This is a feature not a bug.

We don’t start with equivalence class. We start with reps. Then the student asks what they represent?  Then we go to the lowest denominator rep.  Each class is identified with its lowest denominator rep.  There is a 1 to 1 relation of equivalence class and lowest denominator rep.    So use the lowest denominator rep because it is concrete.  Math constructivists would tend to prefer this anyhow.  (Different from math ed constructivists.)

Sign up in comments if you want to join.


About New Math Done Right

Author of Pre-Algebra New Math Done Right Peano Axioms. A below college level self study book on the Peano Axioms and proofs of the associative and commutative laws of addition. President of Mathematical Finance Company. Provides economic scenario generators to financial institutions.
This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s