Form and Function and Food!
Day _______________________________________
Learning objectives:
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Understand how information about form can be used to make predictions about
function.
Understand how adaptations in mouth shape can allow animals to live in different
niches.
Grade 6 standards:
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Formulate questions based on observations that lead to the development of a
hypothesis.
Perform measurements using appropriate scientific tools.
Keep a record of observations, notes, sketches, questions, and ideas such as written
and/or computer logs.
Grade 7 standards:
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Explain how organisms obtain and use resources to develop and thrive in niches
and predator/prey relationships.
Grade 8 standards:
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Describe the following factors that allow for the survival of living organisms: Beak
design.
Introduction (for Teachers):
The primary goal of this activity is to give kids a chance to see how form and
function relate in the important task of energy gathering. For animals, foraging is
essential in order to get enough energy to survive and reproduce. Unlike plants,
animals cannot create their own sugars from the sun's energy, and they must get
energy from plants, animals and other living things. Food webs can help us
understand where energy travels in an ecosystem, but in order to create such webs,
we must have an idea of what every animal eats.
It is not always practical to conduct observational studies of every species to
determine what it eats. Fortunately, we can get some idea of what an animal eats by
examining the structure of its mouth. The shape of an animal's mouth determines
what that animal can eat. Form reflects function, because animals with mouths well
suited for eating their particular diet will survive and reproduce more than an
animal with an ill-fitted mouth. Because form reflects function, by looking at the
form of an animal's mouth, we can make predictions about how that animal gets its
energy. This is commonly used in paleontology, where live animals cannot be
observed, or with animals that are rare and mostly studied through preserved
specimens. If you do not want to kill an animal to get a stomach sample or follow it
around for weeks, checking out how it's built is a good alternative.
Teeth are very informative in mammals. Mammals are unique in having heterodont
dentition, which means they have teeth of different shapes and sizes. Molars, the
large flat teeth found at the back of the mouth, are used to grind down plant
material. Prominent, flat molars are a sign of a diet heavy in herbivory, the eating of
plants. The front-most teeth, the incisors, are also used by some herbivores to snip
leaves and grass off, or used by rodent to gnaw. Canines, the sharp pair of teeth
found between the canines and incisors, are the primary teeth used by predators.
The canines on the top and bottom of the mouth overlap, forming the carnassial
shear, which lets them slice through meat like scissors through paper. Ocean
mammals have specialized teeth as well, some cone-like to grasp fish, or baleen to
filter microorganisms from the water.
Other toothed species have equally interesting adaptions, such as the specialized
fangs of snakes, but birds, which are toothless, show an equally diverse range of
mouth shapes. Early in their evolution, birds lost teeth to reduce their weight in the
air. Therefore, their hard beaks must serve the same purpose as teeth once did.
Carnivorous birds, like hawks, owls and eagles, have sharply pointed beaks that
curve downwards. They use these hooked beaks to tear flesh from bones. The
Loggerhead Shrike is a carnivorous songbird, and it too, bears a hook at the end of
its beak. Birds that eat seeds must have beaks strong enough to break them open,
and they may only be able to eat seeds that fit in their beak. Woodpeckers eat
insects and grubs found below the bark of trees, and have powerful sharp beaks to
drill holes into wood. Some birds, like swallows, catch insects out of the air in their
small beaks with dazzling acrobatics. Pelicans have huge beaks to scoop up fish.
Some birds, like flamingos, even filter-feed, like baleen whales! There are as many
beak shapes as there are diets.
You may want to divide this lesson into two lessons
Materials:
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Altered chopstick-based tongs/mouths
4 bins of tokens
Tokens of various kinds
A large sheet of paper
Tape
Small cups, straws and koolaid.
Assorted specimens of birds or skulls
Before class
o Set large bins around the room full of different tokens of different
shapes and sizes (large round balls, tiny marbles, rubber bands,
rice). Tape a large sheet of paper up on the wall as an additional
station. Place small cups filled with koolaid (enough for each
student to have one) in a bin.
Engage
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20
minutes
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Welcome the students and tell them that they'll be playing a game
today.
Have the students form a group of four that they'll work with for the
game. Give each group a set of "mouths" and each student a straw.
You should have 5 different mouth types in a set.
Tell the students to collect 30 tokens from the bins and place them in
the cup labeled "stomach", which students can take turns carrying.
They must pick up and carry the tokens with the mouths, not their
hands. They must also drink a cup of koolaid or juice without using
their hands (make sure they use the straws for this and make sure
there are enough filled cups for each student to have one). The goal is
to get all 30 tokens safely into the "stomach".
Walk around during the activity. Make sure all students get a chance
to try the mouths. Encourage students who are picking up only one
type of token to try their mouths on different tokens, and students
who are using only one kind of mouth to try the others.
Explore
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20
minutes
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After all 30 items have been collected, have the groups return to their
tables.
Tell the students to pool all their tokens in one large pile on the table.
Tell them to make observations of what kinds of mouths were better
at picking up the different tokens.
While they are doing this, bring out specimens of birds or skulls.
These should be similar in shape to the provided mouths.
Have all the groups pause in their discussion. Explain that you were
poking around in the ASU store rooms and happened to find some
interesting specimens. Show the students the specimens. Do not tell
them what type of animal they are.
Ask the group to be scientists and make observations of the
specimens. Ask the students to focus on how the specimen is similar
and different to their mouths. Tell them to take a specimen back to
their table.
Pass out rulers and other measuring devices.
Let them explore.
Walk around to the tables and ask questions to groups as you think of
them. Try to base them on the conversations the groups are already
having.
o Example questions:
 What kind of animal do you think this is?
 Where do you think it lives?
 What kind of tokens did your group mostly get?
 Did you have trouble getting the tokens back to your
seat?
 What observations are you making?
o Leave your answers open ended. Try to have the students
answer each other, rather than you dispensing wisdom from
above. Do not refuse to give answers, but try to encourage
discussion.
Explain
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20 minutes
When the discussions seem to be winding down or moving to other,
less science related topics, have the groups give a brief presentation
of their mouths and specimen and note any interesting observations
about the mouths and specimen or the token game.
After the groups have presented, summarize briefly the differences
and similarities between the different group's experiences with the
mouths.
Explain that the differences in the mouth shapes affected their ability
pick up the tokens. Briefly review which mouths made it easier or
harder to pick up different "food" items.
This brings us to the idea of how the shape of things can affect how
they work. Scientists call this "form and function". Bring up the week
one PowerPoint for this section.
o For instance, by looking at the shape of an animal's body, we
can get a pretty good idea of how it gets around.
o For instance, we can tell if an animal is fast or not, because to
go fast, animals have to have special adaptions.
 To go fast, animals must have either long legs or move
them very quickly. If you're a tall person, you've
probably noticed you can go faster than someone
shorter. If you smaller, you've probably noticed you
have to really move your legs to keep up with
someone tall. It's the same for animals.
 To make their legs longer, a lot of animals that go fast
walk on their toes. Cats and dogs do this- look at your
pet's foot next time you're home, and you'll see they
put most of their weight on the pad of their feet- their
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toes.
 Some animals go even farther and walk on tip-toethese are the animals with hooves. They can go very
fast.
 Slow animals, like salamanders or elephants just walk
on flat feet.
o But it isn't just feet that are important- many animals have
special adaptations of their skeleton. Cheetahs can run extra
fast because their spine is so flexible it acts like a spring.
So, movement is one thing we might be interested in. What other
important things do animals have to do to survive?
o Get someone to say eat, and if no one does, volunteer it.
Ask questions about how the students eat.
o Are there any foods that students find harder to eat than
others? Jawbreakers, really chewy steak, etc.?
o Does anyone really eat celery easily?
o Does peanut butter ever get stuck to the roof of your mouth?
o When your chips get stale, is it easy to eat them?
o Ask about other things they have trouble eating.
Explain that the shape of the student's own mouths dictates what they
can eat.
o Teeth are used to break down food. If you can't break down
your food, you can't get enough energy, and you'll get really
tired and hungry. How would the students feel if they had to
eat nothing but celery?
o We have special teeth with different functions that work better
with different kinds of food.
o Canines (meat-tearing teeth)
o Incisors (apple-biting, licorice nipping teeth)
o Molars (plant-grinding teeth)
Tell the students that humans get to cheat and use knives and forks,
but animals have to make do with what they're born with. If you are
splitting the lesson in two, then tell them next time we will return to
this topic and discuss how actual animal's mouths are shaped, and
hopefully take a look at some live animals. If not, proceed to Expand
section.
Expand
30 minutes
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Say that birds are an example of animals that need special-shaped
mouths to eat their food. Birds have no teeth, so they don't have
molars, canines, or incisors. Instead, they have beaks that come in
many different shapes and sizes. Beaks are made of hard keratin-
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which is the same material that makes your fingernails or a rhino's
horn!
Ask, "Does anyone know a type of bird that has a really cool beak?"
Draw the coolest (or several coolest) suggestions up on the board.
Ask the students to forget what they know about the bird, and just
look at the shape of its beak. What do they think it eats?
Refer to the specimens the children made observations of. Have them
discuss briefly with their group about what they think the specimen
eats.
While they do this, write a list of foods birds might eat on the board,
or use the week two PowerPoint to display the list. (Note for teachersALL of these are things birds eat except the last 3. FOR THE
TEACHER's INFORMATION, SPECIES THAT DO THESE THINGS ARE
LISTED NEXT TO THE FOOD ITEM. DO NOT GIVE THIS INFO TO
STUDENT UNTIL AT LEAST THE END OF THIS ACTIVITY. THEY MUST
PREDICT ON THEIR OWN.)
o Sunflower seeds (House sparrows, House finches)
o Nectar/sugar water (Anna's hummingbird)
o Fish (Pelicans, penguins, bald eagle)
o Berries (Cedar wax-wing)
o Tiny invertebrates in the water (Flamingos)
o Large fruit like oranges (Orioles, Toucans)
o Meat like rabbits, squirrels, mice (Great-horned owls, Redtailed hawk)
o Lizards (Loggerhead Shrike)
o Snakes (Secretary bird)
o Leaves (Hoatzin)
o Insects and bugs (Tree swallows, Downy woodpeckers)
o Worms (American Robin)
o Other's birds eggs and chicks (American Crows, various
species of gulls)
o Grass seeds (Scaled quail)
o Blood (Oxpeckers)- Yes, there are vampire birds.
o Nuts like acorns (Acorn woodpeckers)
o Twinkies (7th graders)
o Bite-sized snickers bars (7th graders)
o Pizza (7th graders)
Make predictions as a class for the first 2 food items. Ask the students
to suggest what kind of beak shape would go with those items. Have
one student (or several) volunteer to draw these two birds on the
board. Ask students if they agree with the drawing or would make
corrections.
Have the students get out 6 pieces of paper and do their own
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drawings. Have them draw 3 of the listed food items, one to a sheet.
Then have them draw three birds that would eat them.
Have the students switch with another student and see if they can
match bird to food. Or, if you have a projector, display each student's
bird drawings on it and have the other students try to guess what the
bird eats.
Evaluate
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20 minutes
Once the students have made guesses, let them get their 6 drawings
back. Then put up the PowerPoint for week two and move to the first
of the slides that depict unlabeled birds.
Tell the students that we were able to find some birds that ate some of
the listed items, and that their job is to look at pictures of these birds
and guess what they eat. Then you will show the following slide,
which tells them what the bird eats. There are eleven different birds.
Throughout this, discuss the different adaptations these birds have to
their particular foods, or discuss facts about these specific species. By
the end of the slides, the students should be getting pretty good at
guessing what the birds eat.