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13.5: Review of Assimilation

Difficulty Level: At Grade Created by: CK-12
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1. Three important rules that govern the way elements combine to spell words are the Rule of Simple Addition, the Twinning Rule, and the Final <e> Deletion Rule. A fourth important rule governs the changes that occur in the final consonants of some prefixes when they are added to certain stems. The consonants change their sound and spelling to be more like, or similar to, the first sound and letter in the stem. When sounds and letters change this way to be more similar to a sound or letter near them, the process is called assimilation.

For instance, the word assimilate actually contains an assimilated spelling of the prefix ad-: ad + similate = a + s + similate = assimilate . The sound [d] and the letter <d> in ad- change to [s] and to be more similar to – or in this case, exactly the same as – the first sound and letter in the stem similate.

2. All of the following words start with some form of the prefix ad-. Sometimes the prefix assimilated when it combined with the stem; sometimes it combined by simple addition. Analyze each word into its prefix and stem. Be sure that your analysis shows any assimilation that took place when the prefix and stem combined.

Word Prefix + Stem
assimilate a + s + similate
accelerate a + c + celerat
affectionate a + f + fectionate
admirable ad + mirable
allegation a + l + legation
addicted ad + dicted
approximately a + p + proximately
advisor ad + visor
assurance a + s + surance
accumulate a + c + cumulate
advantage ad + vantage
adult ad + ult
applause a + p + plause
advancing ad + vancing
accomplish a + c + complish

3. Other prefixes that often assimilate the way ad- does are sub-, in-, ob-, com- , and ex-. Each one of the following words starts with one of these five prefixes. Sometimes they have assimilated, and sometimes they have combined by simple addition. Analyze each word into its prefix and stem. Be sure that your analysis shows any assimilation that has taken place:

Word Prefix + Stem
accomplished a + complish
collapse co + l + lapse
corruption co+ r + ruption
compliment com + pliment
incredible in + credible
exclusively ex + clusively
effortless e + f + fortless
immigrant i + m + migrant
observance observ + ance
illuminate i + l + luminate
opportunity o + p + portunity
offensive o + f + fensive
irregular i + r + regular
effectively e + f + fectively
occurred o + c + curred

4. When the last consonant in a prefix changes its sound and spelling to be more similar to the sound and spelling at the beginning of the stem, the process is called assimilation.

Teaching Notes.

Item 1. Assimilation is treated in more detail in the following lessons: Book 4, Lessons 12-14 (especially the prefix ad-); Book 4, Lesson 23 (especially ‘tt’ spellings); Book 4, Lessons 34-38 (especially sub-, in, and ob-); Book 5, Lesson 3 (a review); Book 5, Lessons 4-6 (especially com-); Book 5, Lessons 11-13 (especially ex-); Book 6, Lesson 13 (especially ‘rr’ spellings); Book 6, Lessons 36-38 (especially dis- and syn-).

Item 3. You may want to point out to the students the contrast between immigrant (i + m + migrant) with <mm> and emigrant (e + migrant) with <m>.

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Date Created:
Feb 23, 2012
Last Modified:
Jul 07, 2015
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