Another request in the old FB inbox for help with the first-class rank requirements.
I think we all enjoy measuring the heights and widths of things as we motor around our courses.
4a. Using a map and compass, complete an orienteering course that covers at least one mile and requires measuring the height and/or width of designated items (tree, tower, canyon, ditch, etc.).
4b. Demonstrate how to use a handheld GPS unit, GPS app on a smartphone, or other electronic navigation system. Use GPS to find your current location, a destination of your choice, and the route you will take to get there. Follow that route to arrive at your destination.
The rest of 4a at least fits with a normal event or permanent course. And at least I finally know where it comes from, having somehow missed the discussion about First Class vs. Merit Badge when it was on AP in 2016