batch convert iWork 08 files to new version on Yosemite

I just set up my mother's new MacBook with Yosemite and all the new versions of iWork. On her old MacBook she used iWork 08.

Now the new versions of iWork apps won't open her old Pages and Numbers documents telling me that they have to be opened and saved again in iWork 09.

So I installed a copy of iWork 09 I still have lying around, tried to convert a file and that worked. But I don't want to do that manually for all her files, so is there a way to convert all at once? I'm not a stranger to using bash, but I've never used AppleScript or Automator, so I can't figure out a solution myself.

To make things a bit worse, she keeps all her files in a single folder, so I have a folder full of different types of files and if it's possible, I'd like to have a script that takes just Numbers and Pages files (there are no Keynote files) from a certain folder and ignores everything else (mostly pdf,doc,xls,png and jpg)