Target opponent chooses one: artifact creature, non-artifact creature, or non-creature artifact.
Search your library for a card with the chosen qualities and mana value X and put it onto the battlefield, then shuffle.
Learn. "So, what kind of prank are you planning? Froglings? Mechano-froglings? Oh, the old Bag of Froglings, of course."
On The Field1G
When On the Field enters the battlefield, Learn.
You may cast Lesson spells as if they had Flash.
"Be on your toes!"
Sorcery - Lesson
Create two colorless 0/4 Engine artifact creature tokens, with "As long as this is the only attacking artifact, it has power equal to the number of artifacts you control." As Blorgus the Flat learned firsthand, "Potential Energy equals Potential Mass." -Vectormancer's Chant
Name a card. Target opponent reveals their hand and discards each card with that name.
If that player discards no card this way, Learn. I would ask her to stop throwing answers until one sticks, but the spectacle is mesmerizing.
Main note is that "On The Field" is not Green. Green gives flash to Creatures, Red to Sorceries (and Blue is the color of instants, but they don't need Flash) so this is a Red ability rather than Green.
I made On The Field following my instincts, I guess. I'd say about 50% or more of Lessons one casts are the Token producers. And for the rest, they don't usually affect the board (well, Introduction to Annihilation and the Disenchant certainly do.) So when I chose a color to make those effects instant, green felt the most in-pie, in spirit at least. Maybe UG would be more appropriate, but I like where it's at, I think it would be a Lesson-archetype enabler for limited at uncommon, no need to restrict it too much.
Creature - Human Wizard
When Bad Influence enters the battlefield, Learn.
If you would put a card in your hand from outside the game, instead you may exile it. When you do, look at target opponent's hand, and exile a card from it. As long as a card exiled this way remains in exile, it may be cast by a player that doesn't own it, and mana may be spent as if it were any color to cast it.