Birds lay eggs in a variety of sizes. This activity gives students
experience with the relative sizes and volumes of the eggs.
(a) Begin by giving groups of students a large
hard-boiled chicken egg and a tape measure. Ask them to measure
the approximate length and width (distance across the egg when looking
down at it) of their eggs. Compare the answers in the class and
discuss what we would expect as a "typical" size of a chicken egg.
Then ask students to create an egg model using Play-Doh or modeling
clay that is about the same size and shape as the chicken eggs.
Place the model eggs on a scale to find their approximate weight.
This weight, which is based on its volume, will serve as a baseline
for comparing the volumes of several other bird eggs.
(b) The table contains the average lengths and
widths of five bird eggs:
In groups, have the students create clay or Play-Doh models of each
of the bird eggs. Students should account for the general egg shape
and its measurements when constructing the models. Point out that
some eggs are very spherical, while others are more "pointy"; however,
this activity is intended merely to approximate the size and shape
of several eggs.
Have students make predictions about the volume of the eggs. For
example, they might try to guess how the volume of a Canada goose
egg compares to that of a robin egg or how many times greater the
volume of a turtledove egg is than that of a hummingbird egg. They
can also compare the volume of a chicken egg to the volume of the
eggs of other birds. The weight of each model is proportional to
its volume (e.g., an egg's clay model that weighs twice as much
as another requires twice as much material, so it has twice the
volume). Students should weigh each of the models and compare the
weights to determine the relationships between volumes, checking
(c) Students can conduct additional experiments.
For example, the ostrich lays an egg that is 15 to 21 cm long and
10 to 15 cm wide. How many hummingbird eggs could fit inside an
ostrich egg? Use a scatterplot to find out if a relationship exists
between the lengths and widths of bird eggs. Students can also find
the volumes of chicken eggs by measuring the volume of water that
the egg displaces. Another method is to pierce the ends of a raw
egg with a pin and "blow out" the contents. Either measure the contents
blown out, or cover one hole with tape and refill the egg with water,
whose volume can then be measured.
(a) Typical chicken eggs, classified "large" in the grocery
store, will measure about 5.7 cm long and 4.4 cm wide.
(b) Each group might construct several of each
kind of clay "egg" and then distribute them among the groups so
that every team does not have to make all six models.
(c) The volume of an ostrich egg can be estimated
by thinking of it as a sphere with a diameter of 15 cm. In this
example, V = (7.5)3 = 1770 cm³.
The diameter of a hummingbird egg is 1 cm, so its volume would be
estimated as V = (0.5)3 = 0.524 cm³.
Therefore, the volume of the ostrich egg is nearly 3400 times that
of the hummingbird! The points in the scatterplot are roughly linear,
so there is a relationship between the lengths and widths of eggs
of birds of different species.
This activity was modified from National Council of Teacher's of
To look at live egg development in your class, the following, links
you to a unit developed by teachers at R. K. Rutheford School. It
includes introductions for building your own incubator.