Focusing on Word Structure

As we were watching a video about the water cycle, I wrote the following words on the board:

condensation                  evaporation                         transpiration
infiltration                       percolation                          precipitation
interception                     evapotranspiration

What an orthographic opportunity!  The students were quick to recognize that everyone of these had an <ion> suffix.  Next I asked students to say and then spell the word that would remain if the <ion> suffix was removed.  The words listed were now:

condensate                     evaporate                            transpirate

infiltrate                         percolate                              precipitate

intercept                        evapotranspirate

With the exception of the word <intercept>, all the rest had something in common.  The students again pointed out an <ate> suffix.  I asked why the <e> on the end of <ate> didn’t show up once we added the <ion> suffix to the word?  Everyone knew that it was dropped when the vowel suffix <ion> was added.  At this point I recognized though, that some of the students thought the second suffix was <at> instead of <ate>.   In our recent “The Great Suffix Challenge” activity I learned that some of those same students have little understanding of suffixes, other than their position in the word.  We must keep writing out word sums and talking about each morpheme’s role in the word.

Next I asked if anyone recognized any proven prefixes.  Several recognized <inter>, meaning between and <pre>, meaning before.  Even though we had previously discussed <e> being a clip of <ex> (meaning out) and <con> (meaning together), no one recognized them offhand.    I grouped the students and had each group further investigate each word.

As the bases were identified, discussions took us in all sorts of fascinating directions.

The meaning of the word <evaporation> became something we could clearly picture once we knew that <e> was the prefix meaning out  and <vape> was the base meaning steam.  We pictured water evaporating from a tea kettle, a puddle, and a lake.  Our complete word sum hypothesis was <e> + <vape/> + <or> + <ate/> + <ion>.   When deciding whether the base was <vape> or <vapor>, we looked for other words sharing this meaning and found <vapid>.  This word was our evidence that <or> was a suffix.  We decided that without the final <e> on the base, the final consonant <p> would be forced to double when adding a vowel suffix.  Since we know that in words like vaporize and evaporate there is only a single <p>, then we also know there must be a final <e> on the base <vape>.  For those who were confused as to why the base might have a final <e>, I wrote <hoping> on the board and asked them to remove the <ing> suffix.  When they said the base was <hope>, I showed them that the final <e> in <hope> is doing the same job as the final <e> in the bound base <vape>.

Another intriguing discussion arose with the word <infiltration>.  The word sum hypothesis was <in> + <filtr> + <ate/> + <ion>.  As we typically do, we looked for other words that shared the base <filtr> and its meaning.  We found filtration, infiltrate, infiltrator, infiltrated, filter, filtering, filtered, and filters.  Much to my delight, someone asked how we could add an <er> suffix to the base <filtr> to get the word <filter>.  The student knew we wouldn’t just drop the final <r> in the base, but also knew that simply adding the <er> suffix wouldn’t get us the spelling of <filter> either.

The bound base <filtr> behaves similarly to <centr>, <metr>, and <theatr>.  Structurally it makes sense to spell these four with a final <re> rather than an <er>.  Let me give examples using word sums:

<filtr> + <ate/> + <ion> –> <filtration>
<centr> + <al> –> <central>     OR     <centr> + <i> + <fuge/> + <al>  –>  <centrifugal>
<metr> + <ic> –> <metric>       OR    <metr> + <o> + <nome>  –>  <metronome>
<theatr> + <ic> + <al>  –> <theatrical>

In other countries, these words are indeed spelled <filtre>, <centre>, <metre>, and <theatre>.  At some point in American history, the <re> ending was reversed so that these words resembled all of the other words in our language that have an <er> suffix.   Alas! In doing so, another road block to understanding word structure was set in place.  Center and central seemed to be two words that were related in meaning, but not in spelling or structure.  But, of course, that is not what scholarly research and evidence reveals!  My students are now as fascinated with this information as I am.

One final treasure was when we found the base of <transpiration> to be <spire> which means to breathe.  The students began collecting other words with that base and we talked about how each word shared that sense of breathing.  When we studied photosynthesis, we first used the word <transpiration>, and knew that it was that plant action of pulling water up from the roots, through the xylem, through the leaf into the cell and out the stomata.  In this way the plant is breathing.  When we came across the word <perspiration>, the light bulb of meaning connection went off in my own head and I said, “Transpiration.  Perspiration.  Anybody seeing any similarities in meaning?”  Eyes widened and hands shot up.   From there we talked about <respiration>, <inspiration> and <expiration>.  THIS is the stuff you don’t find in spelling workbooks!


“The scientist is not a person who gives the right answers, he’s one who asks the right questions.” ― Claude Lévi-Strauss

While we were learning about water on the earth (what percent of it is salt water and what percent is freshwater), we checked out what percent of our bodies are actually water.  The fact is that approximately 5/6 or 0.83 of our bodies are made up of water.  What an intriguing thought.  It certainly doesn’t feel that way.  We decided to use this information to calculate how many gallons of water were in each of our bodies.

First we each multiplied our weight by 0.83 to find out how many of the pounds we carry around are water.  Then we took that answer and divided it by 8.1 since that is how much one gallon of water weighs.  The answer revealed how many gallons of water each of us had in our bodies.  I had several gallon containers in the classroom so that it was easier to visualize the amounts.  This in itself was interesting and generated quite a bit of discussion. But in my mind I was wondering how does the data collected in this class compare to others?

So I drew a line plot on the board and had the students place an “x” in the appropriate column (we rounded our amounts).  After the first class had listed its data (I teach three classes), the students made some observations and noticed that most students had 9 gallons of water in their body.  The minimum was 6 and the maximum was 14.  The second class added their data to that of the first class so that we were building one huge line plot that represented the entire fifth grade.

By the end of the second class, the mode was no longer 9.  Now 10 and 8 were tied for the mode.  This in itself presented a marvelous opportunity to talk about sample size during investigations!

By the end of the third class, 9 was once more the mode, with 7 and 8 gallons being the second most popular totals.  The maximum and minimum values did not change throughout the day.


After the students left for the day, I created a paper version of the line plot and erased the board.  When they came in the next day, I announced that we were having an estimation contest.  Who could come the closest to guessing how many gallons are in the bodies of all of our fifth graders?  Some of the students immediately got out paper and began using what they remembered from yesterday to calculate a logical guess.  Others just flat out guessed.


In the end, the first place winner guessed within 3 gallons and the second and third place winners (tied) were within 9 gallons.  The prizes were brand new water bottles!  I know.  You could have guessed that, right?  But now what….

As each class met, I let them make observations about our final line plot and the final total.  Then I split them into small groups and had them generate questions.  I wanted to teach them that making observations is great, but the questions you come up with are what take you to the next level.  Great questions are why things are invented,  discoveries are made and the understandings people have grow.  Here are some of the questions the groups came up with:

1.  How many total gallons would be in the students who attend our local high school?

2.  If we calculated the water in all of the students and adults in our building, would the adults have more water or the students?  (Knowing that there are more students than adults)

3.  Would 9 gallons still be the mode if we used 4th graders or 3rd graders?

4.  Our line plot was shaped kind of like a triangle.  Would other grades have that too?  Would any have line plot data shaped more like a wide rectangle? A tall rectangle?

5.  How many gallons of water are in all of the people of the world?

6.  How many gallons of water are in all of the people of Wisconsin?

7.  How many schools full of people would hold the same amount of water as Lake Michigan?

8.  How much more water does a woman have during a pregnancy?

9.  The fifth graders have 576 gallons of water in their bodies.  How long would it take to drink that much water if you drank 64 ounces a day?

10.  What would a line plot look like if the data was collected on newborn babies?

These questions brought such an energy to this simple activity!  The discussions were captivating!

After listening to the students all day, I came up with my own question.  How many fifth graders (the water in them) would it take to fill the school pool?  I explained the next day how I went to the pool director and found out that our pool holds 240,000 gallons.  If we round 576 to 600, that means that I would need to borrow Willy Wonka’s “juicing machine” (from Willy Wonka and the Chocolate Factory by Roald Dahl) and use it on 400 fifth graders to fill our pool!  We all laughed, but found it interesting at the same time.