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.

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.

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