You could use a change event macro that after update
turns off protection, locks the cell, turns on protection
as long as they never look at the macros.
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HTH,
David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001]
My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm
Search Page: http://www.mvps.org/dmcritchie/excel/search.htm

"Simple Gifts" <Simple wrote in message ...
I am trying to make a spreadsheet that can be used for student testing. It
should allow only one entry per cell so that the student cannot continue to
make guesses in the same cell.