Word sum:

Inter + est –> interest

(The prefix + base gives us the stem <interest> )

<Interest> is a Latin word which was borrowed into English from French.  It literally meant “that which is between” – inter “between” +  est “to be”.

It meant ‘to concern, or be of importance’.

Word sums:

Inter + est –> interest

From the above word sum, we see that the stem <interest> is composed of a prefix <inter> and a base <est>.

Why is this important to know? Having this understanding helps students spell the word correctly. 

Students often write the word as *<intrest> instead of <interest>.  When you see several students making the same spelling error irrespective of age or grade, it tells you that they are all processing the word in the same way. <interest> is written as a three-syllable word, but is pronounced with two syllables and that is how they write it.  In speaking, the second syllable loses its vowel ‘sound’ and gets absorbed into the first thus producing a single spoken syllable /intr/

This phenomenon is common in English and other languages as well.  Linguists call it syncope.  Syncope is defined as “the contraction of a word by omitting middle sounds, letters, or syllable”.  Check the spellings and pronunciations of words like family, camera, and every.  In all these examples, students tend to write the words without the second vowel letter, thus producing such spellings: *famly, *camra, *evry.

In these cases, asking students to ‘sound out the word’ or count the number of syllables will not help because when they write, they revert to how they normally pronounce the word (without the second vowel). You have to make them see and understand the structure of the word, and then use the structure to reinforce and strengthen the correct spelling of the word: inter + est –> interest. The second syllable is unstressed and vowel spellings in unstressed syllables are often problematic for students to spell.  The word ‘interesting’ appears frequently in students’ stories and writings and therefore, it is important that they learn to spell it properly.

Let us build some words using word sums:

Interest + s  –>  interests

Interest + ed  –> interested

Interest + ing  –> interesting

Un + interest + ed  –> uninterested

Un + interest + ing  –> uninteresting

Dis + interest  –>  disinterest

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