<p>What size is needed in most cases? The big 9'' by 12'' orange ones or the small white ones?</p>
<p>Lol good question. You might wanna ask your teacher though? xD</p>
<p>My son just used normal business size envelopes (small, white). I have read here on CC that Stanford, though, requires the 9x11 (large, orange) envelopes. You probably should check the admissions websites of the schools you’re applying to, if they want it a certain way there will probably be published information to that effect. I think at most places, though, it doesn’t really matter.</p>
<p>Oh, yes, you’re right for Stanford. I just found the instructions. 
Thanks.</p>