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Unit II Lesson 2


You know what fractions are - I bet you can formulate fractions from an image, and put them correctly on a number line. Do you remember how the same fraction value can take on many different "equivalent" forms and how you strive to put fractions in their most simplified form? (Here is where factors come into play).  This video reviews "least common denominator" - show that you can manipulate equivalent fractions in all their disguises.  But if you are "rusty" on fraction concepts, go to this webpage and review all the exercises on fraction concepts.  It will really pay off if you thoroughly understand the basic fraction concepts.

Now let's DO something with fractions.  We deal with improper fractions, mixed numbers, simplified fractions and more!  

Recall that to add or subtract fractions, you can add or subtract the numerators as long as the denominators are the same: review and try. But what do you do if the denominators are not the same ("unlike" in math terms)? What is the problem?  That brings us to LCM: check out this video, then give it a try with adding and then subtracting.  You can even cope if the fractions have different signs:  see here and then test yourself

Multiplying and dividing fractions is easier:  you do not have to worry about unlike denominators in the beginning fractions. You can watch Sal model what is going on by using area models and number lines.  Watch in this video where you multiply positive and negative fractions. Now watch dividing positive and negative fractions, remember the term "invert?" Now you do a practice multiplying fractions and a practice dividing fractions.  If you are curious about WHY you invert and multiply when dividing fractions, check out this explanation.

Then there are mixed numbers: a whole number plus a fraction.  A mixed number can turned into an improper fraction and vice versa; watch here. What is the difference between improper fraction and a proper fraction? Do you recall how to change a mixed number into an improper fraction? Watch here.  Show that you can go back and forth between a mixed number and its corresponding improper fraction. 

This next video brings decimals together with fractions on a number line, to show how they are interchangeable.  Show that you can put either decimals or fractions as well as whole numbers on a number line.

Fraction and Decimal equivalencies - convert one to the other.  And don't forget to practice doing this with the TI 30XS calculator using the handy toggle key!

 If this material is a struggle for you, go to this website lesson and this lesson too on fractions and spend more time on fractions.  You do need to be proficient in fractions to progress successfully.

In lesson 3, undefined expressions.