Footings are specifically sized depending on your soil type. If they are too small, the house will push into the earth and weight is added. If they are too large, they ca actually be pushed up by the soil beneath, causing the house to shift and walls to crack.
The tops of the footings are constantly checked for elevation. If the top of every footing is level then the rest of the house will be level with very little effort. Crews will actually lift up these frames and shovel dirt around the the base if need be. This makes the footing a little thicker, but makes sure that the top is where it should be.
The pumper truck arrives. This truck will pump the wet cement mix through a series of 4" lines and into the forms.
This is a much larger pump truck than we needed - the company just had this one near by that day. It may have been overkill, but these huge trucks are great to watch.