I'm back again. Now I am trying to figure out this piece of the lesson: "Using the LocationSensor, set up your app to detect if the user is within ten meters of a landmark and automatically open the LocationScreen as they approach it." ?Here is what I have so far, does this make sense?
No
Your blocks in the LocationChanged event are nonsense
Search the community for Haversine formula
https://community-appinventor-mit-edu.ezproxy.canberra.edu.au/search?q=Haversine%20order%3Alatest
Taifun
Ok I'll work on that. Thank you.
You might consider a ringed fence
or
Continuously calculate your distance to a particular location like this Calculer la distance entre son domicile et un point donnée dans une textbox - #2 by SteveJG . When the calculated distance is less than 10 meters, you are there 
You could use a Clock or the LocationChanged event to trigger your calculation.
If you are actually setting Map Markers, you can use some code like
without using an algorithm to calculate distance as Markers have the ability to determine distance to your gps location built in.
Make sure you understand the limitations of using the LocationSensor for determining proximity to a destination (read about Accuracy) in Using the Location Sensor
Ok more homework. Thanks hopefully I can get how this all works. If not I will be back.