Fuiste ayer a la escuela was marked wrong. Harsh?
Why not 'al colegio'? Either duolingo or tinycards is wrong, because school is what tinycards taught me as the meaning of colegio.
Either colegio refers more to college or possibly that colegio and escuela are used in different dialects/countries
why not te fuiste? I thought you used the reflective with the ir verb
In general, ir means to go (You went home. Fuiste a casa.), and irse means to go away, to leave (You left home. Te fuiste de casa.)
Spanishdict.com has lots of examples and alternate meanings.