1.
A toy as a tool for learning is expensive.
A toy, as a tool for learning, is expensive.
Since the phrase is most likely meant to be restrictive, do not use commas.
2.
Ipod as a tool for learning is expensive.
Ipod, as a tool for leraning, is expensive.
It is the writers choice to make the phrase restrictive or non-restrictive. So the commas are the wri