In adding and subtracting fractions with unlike denominators, you have to get a least common denominator which is exactly like the least common multiple it just so happens to be in the denominator.

Find out how to add and subtract fractions with matching and different denominators in this Year 6 article from BBC Bitesize.

Even if students get the basic concepts right—that fractions don’t behave the same way that whole numbers do—the rules of how to operate on fractions can stump learners.

In addition to emphasizing fractions as points on the number line, the common standards differ from previous standards in other important ways: They delay arithmetic with fractions until students ...