Is there a way to teach spells to followers in The Elder Scrolls V: Skyrim? I ask because I noticed Belrand has a 100 in Destruction and Augmented Frost, but apparently he doesn't know any Destruction spells...

Can you do it in the base game? Do you have to use the console and/or mods?

mods are teh only way to do it. AFT is what i recomend personally. it allows complete control of your follower in terms of how and what they do in combat.