Like the inclined plane, the wheel and axle allows
an individual to use less force to move an object be-
cause the force is spread out over a greater distance.
In this activity, the smaller wheel requires more force
to move the bucket than the larger wheel because
the larger wheel spreads the force over a greater
distance; however, turning the smaller wheel requires
less force than turning the rod itself. Teachers can
point out the distance the handle moves on the large
circle compared with the distance the handle on the
small wheel must travel. If children are interested,
they can stretch cord around the edges (circumfer-
ences) of both circles and compare the lengths.
An interesting mathematical component of this ac-
tivity is for children to compare the number of turns
of the large versus the small wheel needed for the
bucket to reach the water. Although the large wheel
itself moves much farther than the small wheel, it does
not move the bucket any farther than the small wheel
does because one rotation of the wheel, independent
of its diameter, completes one rotation of the rod.
Therefore, both wheels must rotate the same number
of times before the bucket reaches the water.
of engineering designs in areas such as the automo-
bile industry. Teachers can help children understand
the importance of this technology by asking ques-
tions throughout the day when children encounter
examples of the wheel and axle, as in the following:
• How would you move the wagon if it didn’t have
wheels? • Is it easier to move this big block by pushing it
along the ground or by pushing it on the wagon?
• How could we open the door without the
doorknob? Comments and Questions
to Support Inquiry
• How many times do you need to turn the big
wheel before the bucket reaches the water? How
many times do you need to turn the little wheel?
• Does the bucket move farther when you move the
big wheel one time around versus the little wheel?
Let’s put a stick in the well and mark the distance
the bucket moves when we move each wheel one
• What makes the bucket move?
Connections to Technology
The wheel and axle is itself an example of technology
that has evolved over thousands of years yet is still a
fixture of modern life. It is an important component
Not every wheel mounted to a rod constitutes
a wheel and axle. In a true wheel and axle, the
rod and wheel are firmly attached so that when
one rotates, so does the other.
ST E M lE aR n I ng c E n T E R S