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7.23: The Sound [t] and Assimilation

Difficulty Level: At Grade Created by: CK-12
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The Sound [t] and Assimilation

1. Earlier you saw that when the prefix ad- is added to a stem that starts with a <t>, the <d> assimilates: It changes to a <t>, making two <t>'s: ad + t + tain = attain.

When the prefix ad- is added to a stem that starts with a <t>, the <d> assimilates and changes to a <t>.

2. Here again are the nine words from the last lesson in which [t] is spelled <tt> .


There are two words in the nine that contain the prefix ad- and a stem that starts with a <t>. Find them and analyze them to show the assimilation that gives us the <tt> spelling, as we have done with attain:

Word = Assimilated Prefix ad- + Stem
attain = ad + t + tain
attention = ad + t + tention
attend = ad + t + tend

3. Now sort the nine words into the following three groups:

Words in which the
simple addition assimilation twinning
cattail attention committed
outtalk attend submitted

Among the nine words in Item 2, the word in which the <tt> is not due to either simple addition,assimilation, or twinning is bottom. We will talk about words like this one in the next lesson.

4. Analyze each of the following words to show where the <tt> spelling comes from:

Word = Analysis
outtrick = out + trick
attracts = ad + t + tract + s
knotty = knot + t + y
quitter = quit + t + er
attempt = ad + t + temp
outtake = out + take
rattrap = rat + trap
regretted = regret + t + ed
permitting = permit + t + ing
attendance = ad t + tend + ance
fattest = fat + t + est
fattiest = fat + t + y + i + est

5. Three reasons for [t] being spelled <tt> are simple addition, assimilation, and twinning.

Teaching Notes.

Item 4. Technically, there is more explication done in the suggested solutions than is necessary to show where the <tt> spelling comes from, but it seems worthwhile to have the students analyze out the suffixes. If nothing else, it underlines the difference in structure between fattest and fattiest.

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