Did you know there are three types of map scales? I didn't until I found this article from the San Francisco Estuary Institute and Aquatic Center. I knew about the first two but the third one? I'd never heard of. I usually teach a little bit about scaling during the unit on ratios but I'd never done much with maps.
The three types are verbal, graphic or bar, and RF or representative fraction scale. They give great examples, talk about converting from one to another type, and include information for calculating the scale from a picture or map. This is a wonderful real life application of ratios and scale. They even talk about flat vs non flat areas when calculating scale.
Furthermore, this article goes on to discuss finding area and distance using both the map and the scale. I love the fact they take time to discuss four different types of measurement used in the field and even go so far as to discuss accuracy, precision, and significant digits. Although it is just an informational article, it is filled with lots of examples.
So with this information, you could use a prepared worksheet such as this one that has you estimate and then calculate distance on a map that has a only one type of scale. It wouldn't be hard to add another page where they have to convert to the other two scales. It might even be possible to find something in Google Streetview that the students could use to practice calculating distance based on the picture you are looking at.
What about an online game that allows students to practice measuring distance on a map and then calculating the actual distance using a world map? Perhaps you could add a worksheet to this so the students write down starting, finishing, distance measured, actual distance so once they have done say 10 locations, they can calculate the predicted time it might take to fly between the points based on average airplane speeds. This is a real life application for map scales and rate x time = distance.
More tomorrow on this topic.