Then make a simple altimeter.

It is actually a small barometer.

Find a transparent glass bottle.

Foam plug with small hole in the middle

A thinner straw.

There is half a bottle of water in the bottle.

The straw is inserted into the plug.

Plug the bottle.

The bottom of the straw should be below the liquid level.

The whole device should ensure no air leakage.

Blow into the straw

Make the liquid level in the tube higher than the bottle stopper.

Take this bottle upstairs.

Each layer is marked with a pen on the straw.

The height of the building can be judged according to the height of the liquid level in the straw.