Name: _______________________________
Earth rotates on its axis.
Earth Science
Making Claims:
If someone told you to figure out how the Earth was rotating on its axis, what would you do? How
could you figure out what to do? How do scientists figure it out? Would you believe that the direction
of the water in this toilet bowl was influenced by the Earth's rotation? Didn't think so.
RYAN MCVAY
Philosophers, scientists and astronomers have been tackling life's most pressing questions since the
beginning of time. They've convinced us that the Earth is indeed round, that it revolves around the sun and
that it rotates on its axis once approximately every 24 hours. However, they can't seem to agree on the role
that rotation plays in the way toilets flush and baseballs travel.
Popular culture has actually taken on the flushing toilet puzzle before. In a classic episode of "The
Simpsons," Lisa convinces a skeptical Bart that drains in the Northern Hemisphere always empty to the left
(counterclockwise) and those in the Southern Hemisphere empty to the right (clockwise).
The premise for this vexing question is a phenomenon known as the Coriolis effect. Basically, the Coriolis
effect refers to the way that the Earth's eastward rotation influences how we see the direction of travel of
certain moving objects. At the equator, where the Earth is about 24,900 miles (40,076 kilometers) in
diameter, land moves at more than 1,000 miles per hour (1,609 kilometers per hour). As we move closer to
the poles, land moves much slower. At 60 degrees north latitude, for instance, land moves at around half
that speed.
In the Northern Hemisphere, this means that an object traveling from the equator toward the poles will
appear to veer to the right because it maintains the greater momentum of its place of origin. On the return
trip, the object would again turn to the right -- this time because it didn't have as much initial momentum.
In the Southern Hemisphere, the effect is the opposite; objects would veer to the left.

Evidence–based Journal
Claim: The Earth rotates upon its axis
Coriolis Effect
So What? What is the scientific concept that
What is Your Evidence?
links each piece of evidence to the claim?
Refer to the rubric to see how you will be graded.
Rubric for
Criteria
Exceeds expectations (3)
Claim (Outline)
Claim made and
described in a way that
demonstrates sound
scientific reasoning
More than two pieces of
evidence (including
textual and data table)
Explanation given for all
evidence
Evidence (Outline)
Scientific
Reasoning
(Outline)
Scientific
Explanation
(paragraph)
Written in complete
sentences with no
grammatical/spelling
errors
Making Claims: Earth rotates on its axis.
Meets expectations
(2)
Claim made and
evidence is given,
although reasoning is
unclear
Two pieces of
evidence
Approaching
expectations (1)
Claim made
Did not meet
expectations (0)
No claim made
One piece of
evidence
No evidence
Explanation given for
some evidence
Explanation is not
relevant to the
evidence
Written in complete
sentences with
some
grammatical/spellin
g errors
No explanation
attempted
Written in complete
sentences with few
grammatical/spelling
errors
Not written in
complete sentences.