what are the minimum operating systems for a MAC laptop and iPad? I am using a macbook air 2010 with OS X Yosemite and some of the material is not showing up. The same happens on our older iPads. Very frustrating when the submit button is not on the screen or the assignments are not loading. I cannot find the basic operating system requirements on the help pages. I am trying to upgrade the MAC operating system but I am not sure if it is capable of getting the newest Catalina so the minimum operating system requirements to avoid these glitches would be good to know. Thank you.