[Tutor] Design question: Web-based vs. desktop-based vs. desktop-based with data backed up to web server with a tablet thrown in for all cases?

[boB Stepp]

My wife (a Montessori teacher of 7th through 9th grades) is trying to
coerce me to create some helpful software for her classroom.  She has
lots of things she *wants*:  Some involve only her and her record
keeping.  Some will involve both her and students.  Some would
additionally involve parents.  With the parents it would have to be
web-based.  For students, some software would be used only in their
classroom.  Others would be used both in and outside the classroom.
In my wife's case, she would want to be able to access the software
and its data either at school or at home.  Currently she does most of
her work on a laptop that she carries back and forth between home and
school.  Anything involving student records would have to be kept
secure.

For her most urgent project to be done before school starts in 5 weeks
(!), she wants me to enable her to assess her students' work as she
wanders about the classroom using this Samsung Slate tablet the school
has given her to use.  This device would be okay for stuff like
checking check boxes, navigating menus, radio buttons, drop-down list
boxes, etc., but would be horrible for any type of manual data entry.
So she would need to do the latter at her laptop, though she might do
limited data entry on the tablet.

I do own server space and a domain name that I have never used, but
should be adequate for my wife's needs.  The school has a wireless
network that allows Internet access, which is usually (but not
always!) reliable.

The main question:  How do I best handle the storage and access of my
wife's classroom data in these three different scenarios (wife's
access only; wife and student's access; wife's, student's and
parent's), and have each party to have access to relevant software I
create?

Using this *most urgent* project as a starting example, this student
assessment software would involve only my wife, the tablet and her
laptop.  Both the laptop and the tablet would have to both be able to
run the software and have synchronized data between the two devices.
If the student data resided only on these two devices, then protecting
the student data isn't as much of an issue as long as my wife controls
her physical devices.  However, if the data were to reside on a server
then that would become a more important issue.  It would obviously be
very important that data cannot be lost.  I can easily imagine my wife
dropping and destroying the tablet, the tablet's hard drive crashing,
the laptop's crashing, etc.  If the data were stored online, then
possible school wireless network outages would be a potential bad
problem.

My best thoughts at the moment are to:

1) Find a way to always keep the laptop and tablet synchronized.
2) Have both devices write a backup copy of the data to the server
whenever a change in the data occurs.
3) In case of wireless network failure, the software would realize
this and know that whenever connectivity is restored to write any data
that has changed in the interim.
4) The backup data on the server would have to be securely encrypted
against whatever hackers might try to to access or intercept the data.
(Hmm.  What about the communications between the laptop and the
tablet?)

Is this a sensible way of approaching at least this one project?  Of
course, I have not a clue as to how to do any of this (yet!).

As always, many thanks in advance!

P.S.:  My wife has researched existing software and has found
everything lacking.  She wants custom solutions to her custom needs.
Oh, joy.  But very interesting!

-- 
boB