Affixes – Rules of use

When it comes to teaching students about affixes, there are certain rules and notes which can be useful to learn.

These rules can enable students not only to decipher the meaning of certain words, but also to create their own words without help. This might not seem like such a big step, but it’s a huge moment in a student’s journey when they first piece together a new word for themselves, and can give them a great sense of achievement.

Prefix Rules

Students will often struggle to match prefixes with compatible base words. For example, it’s easy for a native speaker to see that “unlegal/imlegal” is incorrect, however, new learners won’t be aware of this.

Luckily, when it comes to negative prefixes (ones that change a word to hold an opposite meaning) there are a number of rules which can be applied in most situations for matching suitable prefixes with base words:

Rough negative prefix rules:

Words starting with ‘l’ have the prefix ‘il’ – illegal, illegible
Words starting with ‘r’ use the prefix ‘ir’ – irrelevant, irresponsible
Words starting with ‘m’, ‘b’ or ‘p’ use ‘im’ – impatient, immature, imbalance

This won’t help students to match all base words with a correct prefix, but it’ll help when dealing with many negative prefixes – which are one of the most common uses.

Suffix Rules

Suffixes can be tricky, as there aren’t many rules that can be widely applied, however there are a few points that students should be made aware of.

First, students should know that unlike prefixes, suffixes can change the spelling of the original word. This can often make it difficult for students to pick out the base word from the suffix itself.

For example:

Beauty + ‘ful’ = beautiful

Second, similar to prefixes, not all suffixes can be applied to all base words. However, with suffixes there’s less of a structure to which words can take which suffixes, and your students will have to learn and memorize these on a word-by-word basis.

Third, each suffix can have a different meaning depending on what type of word it is attached to, and these will also have to be memorized.

For example:

‘er’ + big = bigger (more big)
But
‘er’ + train = trainer (someone who trains)

As these can be a little complicated for new teachers, in the next page we’ll look at some further tips for introducing affixes to your students.