Creating "alerts" when taking attendance in Excel 2007

Hello! I am using a giant spreadsheet to take attendance for my after school programs. This year, our principal has made it mandatory that students show up for Monday and Tuesday to be able to come to Wednesday fun stuff. I would like to be able to quickly see when a kid doesn't show up for M/T, but does come to Wednesday.

I am taking attendance using an initial for each program so if a 6th grader comes to reading on October 5th, they get a "6R" in the 10/5 column. So if a function could make the week could turn red or check a certain box when they come to Wednesday without coming to Monday or Tuesday, that would be perfect.

Thank you for your help!

I'm not sure how you intend to lay out your data but here's a shot at it.

Col A Col B Col C Col D Col E Col F
Student Name Grade Monday Tuesday Both? Wednesday
Jane Doe 6 6R 6R 2 1
John Doe 5 5R 1 1
Sally Smith 5 5R 1 1
Nancy Johnson 5 5R 5R 2 1

The formula in cell E2 is =COUNTA(C2:D2)
Cell F2 has conditional formatting to turn red if the "1" you enter is equal to or less than the formula result in cell E2

Oh YES! Thank you! Going to attempt this now...