I asked Remind– a teacher-student communication app– to remove pings to Facebook ads, DoubleClick.net, and Google Ad Services from their site when students viewed messages. Allegedly they were being used to track the performance of ads they bought, and that the ad companies promised in their ToS not to use it for ad targeting. They were polite and removed it after 2 weeks. Last time I checked they added Twitter ads analytics again...
I would say a lot of schools themselves add those things, just to do analytics. Heck, my doctor's website has google and doubleclick links - on the pages where I'm communicating with my doctor, or viewing test results! I complained and they said "our website is a convenience"
