Station 1

The first stop is the transit (dumpy) machine at the edge of the open trench. When an avatar hops on it, the avatar's camera is relocated so the stadia rod on the other side of the trench is visible. The transit machine then whispers to the avatar:

ROMA Transit Machine: Look at the black and white measuring staff at the other side of the trench. If each bar on the staff measures 20 centimeters, how many centimeters is it from the top of the staff down to the top of the pebbly layer (where the red arrow is)? Say the number only in open chat.

It then waits for the avatar to say the correct number of centimeters. When they do, it congratulates them:

ROMA Transit Machine: Correct! The top of the pebbly layer is 140 centimeters from the top of the staff. With this machine, the archaeologist can record where each layer exists in space.

It then gives the avatar a special GPS Device Gadget and directs them to climb down into the trench to the next station.