I can add some suggestions to simplify the look of this workbook and pretty it up a bit.

1. Create named ranges for “upper” and “lower” alphabets:
upper=INDEX({“A”,”B”,”C”,”D”,”E”,”F”,”G”,”H”,”I”,”J”,”K”,”L”,”M”,”N”,”O”,”P”,”Q”,”R”,”S”,”T”,”U”,”V”,”W”,”X”,”Y”,”Z”},RANDBETWEEN(1,26))
lower = lower(upper)

2. In A1 create a dropdown for “Upper” and “Lower”

3. In A2 make a single cell, named “letter” with font size 200 and formula =IF(A1=”Upper”,upper,lower)

4. Add code to the sheet1 module to randomize the letter in all 56 colors
Private Sub Worksheet_Calculate()
[letter].Font.ColorIndex = [randbetween(1, 56)]
End Sub

5. Optional but you could then set your 56 workbook colors to selected colors
For example, stick the following index numbers in A1:A56 and run this bit of code
activeworkbook.Colors = application.transpose(Range(“A1:A56″))

16759603
16316664
16764057
11141119
4949955
12961279
16768701
10878885
16759413
6946815
3897009
13541094
9812223
3407769
15395562
12632256
16772571
16767669
13434828
13882367
13434879
9043849
15395562
12632256
16762509
16757349
13209
11711154
9868950
7829367
5066061
2697513
10338015
13434828
13434879
14145535
12703467
16773087
13231359
16737843
8103891
7733109
13937151
13382451
10040115
10053222
5995263
14540253
47240
10092543
65535
16744917
6697728
11655423
5263615
11711154

If I ever have to design an elementary school curriculum, I’m hiring you

I’ve updated the file with your suggestion with two slight variation. I’ve added the option to have the colors or not. Also, for the 3 conditions you don’t need to put AND(D2>.50,D2<.75), D2<.75 is sufficient if the conditions are in proper order.

i.e.:
Condition 1: <0.25 is evaluated — if it is TRUE, then it stops and format is applied
Condition 2: <0.50 is evaluated — if it is TRUE, then it stops and format is applied
Condition 3: <0.75 is evaluated — if it is TRUE, then it stops and format is applied

If you're using Excel 2007, you need to check "Stop if True" for each conditions in the "Conditional Formating – Manage Rules…" dialog.

Oh! I also changed the reference cell to a new one because I didn't want the bias of always having the letter A in blue.