im not an FI
but i'd go with the chalk and talk.
all very well having a flash powerpoint, but sod's law says that it will probably break when you want to use it
plus ur not stuck using to same slides if someone doesn't understand, you could draw different perspectives etc without having to format and all that jazz.
although you could have an exeptionally good powerpoint, half the time you'd need a bloody type rating just to set everything up and hope it stays that way for your whole FI journey.
gd luck with whichever you use though!
When im doing my FI it will prob be chalk/board markers though.