We add the endings -er and -est to words when we want to compare things.

The purple car is old,  but the orange car is older and the black car is the oldest.

If the word has a short vowel sound just before the last letter, we double the last letter before we add the -er and -est.

big / bigger / biggest

If there are two consonants (letters that are not vowels) after the short vowel sound, we don't double the last letter.

long / longer / longest

If the vowel sound is long, we don't double the last letter.

cheap / cheaper / cheapest

Finally, there are some words that don't obey the rules at all!

good / better / best

bad / worse / worst

Let's have a go at some questions now.