Really a classic (well, they all are), Mario's plumber license, as well as his carpenter license seem to have been revoked since he was forced to apply for a job in a cement factory. At the top of the screen two conveyer belts deliver packages of cement to the left and the right side, dropping them in the cement containers, each container can hold up to three portions and Mario's job is to make sure the containers don't overflow, simply walk over to them and push the 'open' button, a hatch underneath the container will open and the cement will proceed to a lower level. After the top container on either side is emptied you will have to repeat this process for the lower containers, after which the cement finally reaches the lorry, driven by undoubtedly relatives of Mario. When you spill cement the lorry driver directly underneath falls out.
In the middle there are two elevators the left one is going down and the right one is going up, these are obviously needed to get from one side to the other and to change floors. Standing on the elevator when it reached the top or the bottom of the screen, results in certain death. Jumping on a elevator when it's one level lower is also advised against. At the bottom left there is a small plateau where you can flee to if your elevator almost disappears in the ground, you can then wait for a better opportunity to take the next one. The negotiation of the elevators is much more difficult than keeping track of the cement, you will sacrifice most of your lives to them.