Formation of letters with Whiteboard Apps

I was talking to a junior teacher today about ShowMe and all the things she could do with it in Maths. She started thinking about how she could use it for letter formation practice. She lets the students practise on the Whiteboard but if she is not standing over them at the time, she doesn't see whether they are forming them correctly.
Some of the following 'Whiteboard' apps are ideal for students to practice their letter formation as they can record what they are doing and the teacher can view it later.

ShowMe (Free for the iPad)
Account: You need to set up an account to save recordings. Students can set up their own accounts if they are using their own iPad or you can set up a class accounts.
Preview before saving: No
Saving: Tap on the padlock to make a ShowMe private, otherwise it will get published to your public ShowMe account on showme.com
Example of ShowMe

Educreations Interactive Whiteboard (Free for iPad)
Account: You need to set up an account to save recordings. Students can set up their own accounts if they are using their own iPad or you can set up a class accounts.
Preview before saving: No
Saving: Tap Done, choose a category
Example of Educreations

Screen Chomp (Free for iPad)
Account: No account necessary but you can login with Facebook
Preview before saving: Yes
Saving: Tap on the screen chomp icon and it will save

In the classroom, I would probably find Screen Chomp at this particular time the best app to use if you do not want to save what the students have done. Students can record what they are doing and then playback to you without saving.