Top heavy or sidecar?
Converting between '1 1/2' and '3/2'.
Improper fractions are easier for algebra; Mixed numbers are easier for cooking.
MAD: Multiply, Add, Denominator stays same.
In Plain English: An improper fraction is 'Top Heavy' (bigger number on top). It means you have more than one whole item. 3/2 means you have 3 halves... which is 1 whole and 1 half left over.
In The Real World: Buying lumber. You buy '2 by 4s', but often need lengths like 8 1/2 feet.
Forgetting to keep the denominator the same when converting.