Japanese particle: de

で
Used in Unit 2 in the middle and latter half of the Unit
One use seems to be as a particle that means 'by way of' or 'using'

Like, 手で is used when something is done by hand, or left or right hand if it's done with one hand or the other (左手で).  1-2-5, I think.

Used when describing what something is doing with their head, and the hands are used to do it.
1-2-9