Hello again Alessandra,
I'm very happy to hear that using the web app instead to add this activity in the meantime has enabled you to prepare tomorrow's lesson.
As discussed via email, this problem occurs in the current release of our iPad app and it has already been fixed in the latest version of the app, which will be available on the AppStore soon. Be sure to update to the latest version when it comes out!
Apologies for the inconvenience, and thank you once again for bringing this to our attention.
The EF Class Team