QUESTION: 
Does Mars have a crust, mantle, and core like the earth?

ANSWER from the Internet on January 13, 1997:
http://seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html

The interior of Mars is known only by inference from data about the
surface and the bulk statistics of the planet. The most likely 
scenario is a dense core about 1700 km in radius, a molten rocky 
mantle somewhat denser than the Earth's and a thin crust. The lack of 
a global magnetic field indicates that Mars's core is probably solid. 
Mars's relatively low density compared to the other terrestrial 
planets indicates that its core probably contains a relatively large 
fraction of sulfur in addition to iron (iron and iron sulfide).

Like Mercury and the Moon, Mars appears to lack active plate 
tectonics; there is no evidence of horizontal motion of the surface 
such as the folded mountains so common on Earth. With no lateral plate 
motion, hot-spots under the crust stay in a fixed position relative to 
the surface. This, along with the lower surface gravity, may account 
for the Tharis bulge and its enormous volcanoes.

ANSWER from Jeff Plescia on January 31, 1997:
The assumption is that the core of Mars is made of iron. But we
don't know. We infer that from the planet's shape and it's
gravity.

We can only see the surface and have no samples of the interior.
It's the same process as we use for the Earth. The hypothesis is
that the core of the earth is iron (an inner solid iron core and
an outer liquid iron core).

Ask your teacher to explain moment of inertia and how
you can use that to tell about the interior of a sphere.