A prefix is a word part (morpheme) placed in front of a base word to form a new word. Prefixes change the semantic meaning of the affected word. For example, if we add the prefix un- to the base word ‘kind’, we will form the negative ‘unkind’. Here are more examples of prefixes: non (existent), il (legal), im (patient), un(sure), dis(solve), ir(responsible), mis(understand), in(humane), over (cooked), and re(done).
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There are about 90 (ninety) prefixes in English, and we can’t probably teach them all at once but we can start by the most common ones: ‘un’ and ‘re’. Here is a fun video which provides context to the meaning of these two prefixes:
What do students need to know about prefixes?
Simply, the meaning they add to the root or base word, and how to spell them, which, at the same time, are the possible difficulties students may find when learning prefixes. Prefixes such as non, il, im, un, dis, and ir mean ‘no’. So, it is quite easy for them to confuse these combinations. They may say ‘un-legal’ for ‘ illegal’, or ‘unresponsible’ for ‘irresponsible’. Why not, right? Well, it does not work like that in English. Considering that some prefixes have the same meaning, a way to help students understand and remember meaning could be group them under the corresponding category as for example, the NO group ( as in the example above), or the “TOO MUCH” group as in ‘overcooked’, ‘overdone’, ‘overbooked’, etc.
As for spelling, we need to show students that there are some cases where they will need to double the consonants, or hyphenate them: unnecessary, illogical, immature, ex-president, co-owner, etc.
But, not all syllables which contain the same string of letters as a prefix are prefixes. Words such as ‘under’, ‘undulated’, ‘uncle’, for example, are not the negative forms of ‘der’, ‘dulated’, or ‘cle’. This must be easy to understand at an intermediate level but not at lower levels. So, make sure that when teaching prefixes your students can clearly see the root or base word.
Word building, gap filling, matching prefixes to base words, and classifying tasks are some of the many activities you can use to practice prefixes with your class.