As from 4th October 2016 Dropbox, in its infinite wisdom, has decided to disable embedding of htm files within a browser.
That means that all the interactive exercises linked from dropbox on this blog do not now work.
None of them.
Sorry about that.
It looks like you get a automatic htm download if you are using firefox but otherwise there is now just a black space where once there was an exercise.
Many of the exercises are downloadable as word docs but nothing here is interactive anymore.
Dropbox has given no reason for this change.
Thanks a bunch dropbox.