If you are old enough, there was always someone in the family who built a huge 4 by 8 railroad using models. I remember seeing one in the family with a town, forest, bridge and a lake as part of the journey.
If the builder did things correctly, everything looked perfect because the scales remained the same for everything. If not, the trees might be a bit too small and the lake more like an ocean.
Did you know the scales for model railroads were not always the same? I didn't until I researched this topic. The National Model Railroad Association has some excellent information if you want to read about this topic in more detail.
In model railroading, scale means it is a smaller version of the real thing. O scale is also known as 1/4th inch scale which is a ratio of 1 to 48 while the HO scale is 1/8th inch scale with a ratio of 1 to 86 or 1 to 87. The N scale made its appearance in the 1970's and has a ratio of 1 to 160 while the Z scale has a ratio of 1 to 220. This means the O scale is the largest while the Z scale is the smallest.
Another one, the S scale as defined in 1943 is 3/16th inch or a scale of 1 to 64. At one point this scale almost disappeared but has undergone a Renaissance.
There are a few others but these are the main ones. Now to add to the confusion, one has to keep in mind, one has to keep in mind the gauge or distance between the rails. For instance, the distance between the rails for the O scale is a bit more complex because it normally requires 3 rails instead of two and the distance represented is 5 feet.
Its all a bit confusing if you are not familiar with this topic because the distance between the rails must also be done properly so everything looks proper. So what do you do with this information? It makes a good project involving research and drawings which are properly scaled. As part of the research, students can determine which scale is used with which manufacturers or the train such as American Flyer or Lionel.
I have been traveling and this is being written in an airport between Fairbanks, AK and Burbank, CA. I'm at a conference till Monday when I head home.