In this practice, you need to adjust a "gauge" to indicate the surface normal direction. Here is what is normal from wiki Normal . A gauge is a circular disk with a normal direction indicator.

a gauge example

The above picture shows an example of which is good and which is bad for using a gauge to indicate the surface normal direction. In the picture, the specified surface normal is facing right, so the left gauge is a good indicator.
On the other hand, the right gauge is a bad indicator since its direction pointing to the front.

a circular disk gauge example

Circular disk on the upper right of the appears good, but the one on the lower left does not.

There are two practising objects:

Sphere

Arbitrary Object