Title: What Big Teeth You Have: A Comparison of Marine Fossil Teeth and Human Teeth

Author:  Kari Poppen, Taylor Prairie Elementary, Monona Grove, WI

Grades:  1-3

Overview of Lesson: Children compare and recognize the function and appearance of sharp and flat teeth.  The lesson focuses specifically on the teeth of marine reptiles from the Late Cretaceous Period and the childrenıs own teeth.

Suggested Time:  20-25 minutes

Students' Prior Knowledge:  Before talking about the teeth of marine reptiles from the Late Cretaceous Period, the class makes observations of their own teeth.  Each child uses a small handheld mirror to observe their own teeth.  Then each child works with a partner and does a "think, pair, share." This is a time when the children work in small groups and share their observations with another child.  At this time, each child will also observe their partnerıs teeth.

After completing "think, pair, share", the class shares its observations.  As a class, they discuss the function and appearance of human teeth, noting that some are flat and some are sharp.  Predictions are made about the functions and appearance of marine reptilesı teeth.

Background Information:  Over time Kansas has changed.  During the Cretaceous Period, Kansas was an interior seaway.  At this point in the lesson, the class makes comparisons between modern day Kansas and Kansas during the Late Cretaceous Period.  A Venn diagram is used when making this comparison.  Marine life in the Niobrara Formation during the Cretaceous, namely the mosasaurs, sharks and fish like Xiphactinus, is identified and discussed. Children learn that not all dinosaurs and ancient vertebrates ate the same thing. Some ate plants and some ate meat.

Materials:
model dinosaur teeth
model mosasaur teeth
student science writing journals
peanut butter
honey
nonfat dry powdered milk
                          


Student Activity: After observing their own teeth with some mirrors and making predictions about the teeth of marine reptiles, the class begins the activity of comparing sharp and flat teeth.

Each child needs a small ball of peanut butter play dough.  As a group, they add to a large bowl all of a small jar of smooth peanut butter, 3 tablespoons of honey and a cup of powdered milk. Mix this mixture thoroughly with a wooden spoon.  Each child spoons out a ball and uses their hands to flatten the mixture into a flat pancake.  

Then each child presses one corner of the mixture against a back molar in their mouth and then against a sharp-edged corner tooth. The children observe their teeth impressions.

Each child shares their observations with a partner.  The children then record their observations in their science writing journals. This activity is designed to initiate a class discussion which helps the children see the difference between flat and sharp teeth. the class discusses how sharp teeth are perfect for ripping and tearing and the flat teeth are ideal for grinding plant material.

After making impressions of their own teeth, the class observes the teeth of dinosaurs and mosasaurs. As a group activity, the class makes impressions of these fossil teeth in the molding mixture.  The sharp point of the tooth is compared to the prongs of a fork or the blade of a knife, whose function it is to cut meat.  The flat teeth are more dull and can be compared to the back of a spoon.

To conclude this activity, the children are given the following question to answer and write in their science journals.  "If you found a marine fossil with sharp, pointed teeth, what would you predict that it ate?" The written responses help assess the childrenıs understanding of sharp and flat teeth functions.


Teacher Notes:  The materials for peanut butter play dough can be purchased at a grocery store. In this lab activity, honey replaces the sugars used in the recipe. This recipe was found in the Teacherıs Guide of the Dinosaur Museum, published by Harcourt Brace, 1995
1 1/2 C powdered milk
1 1/4 C powdered sugar
1 C        light corn syrup
1 C        smooth peanut butter

Mix well. Knead well. Chill overnight. Shape and eat or save in sandwich bags.  

The model teeth can be purchased from a science supply store like Carolina Biological or Wards.

Vocabulary:  grind, tear, flat, smooth, mold, imprint

Interdisciplinary Connections:
Math- using a ruler, comparing size, graphing teeth lost, graphing plant vs. meat eating dinosaurs.
Art- drawing teeth, making clay models of teeth, making ³baseball cards² of different dinosaurs.
Writing- recording observations, writing stories about animals with teeth.

Extension Activities:
* observe and compare the tooth of a cow and a shark
* at the writing center, ask the questions "what would it be like to be a dentist of a mosasaur?" or "how would a tooth fairy visit a mosasaur?"

Wisconsin State Science Standards:
A.4.1
http://www.dpi.state.wi.us/standards/scia4.html
When conducting science investigations, ask and answer questions that will help decide the general areas of science being addressed.
A.4.5
http://www.dpi.state.wi.us/standards/scia4.html
When studying a science-related problem, decide what changes over time are occurring or have occurred.
B.4.1
Use encyclopedias, source books, texts, computers, teachers, parents, other adults, journals, popular press and various other sources to help answer science-related questions and plan investigations.
C.4.1.
http://www.dpi.state.wi.us/standards/scic4.html
Use the vocabulary of the unifying themes to ask questions about objects, organisms and events being studied.
C.4.2
http://www.dpi.state.wi.us/standards/scic4.html
Use the science content being learned to ask questions, plan investigations, make observations, make predictions and offer explanations.
C.4.4
http://www.dpi.state.wi.us/standards/scic4.html
Use simple science equipment including rulers, balances, graduated cylinders, hand lenses, thermometers and computers safely and effectively to collect data relevant to questions and investigations.