Before it
Instruction tuning had been shown on dozens of tasks at moderate scale.
The problem
Did it keep working with more tasks, bigger models and reasoning data mixed in?
What it introduced
Scale to 1,800 tasks and add chain-of-thought examples to the instruction mixture.
Why it matters
It made instruction tuning a scalable recipe, and the released Flan-T5 models became a research workhorse.
What modern models inherit
Instruction mixtures that include reasoning traces.
What came next
The Flan collection fed open instruction datasets; the recipe is standard post-training practice.