Excel tries to be helpful, to make your life a little easier.  One of the things it tries to do is to automatically enter data for you, (if it can guess what data it is you«re trying to enter, that is.)

One of the things it is quite good at is entering the correct time, or day of the week.  All you have to do is to give it a clue by starting it off.  Like this...

The accompanying task will ask you to do this yourself. Remember, the "Fill Handle" is the little black "box" in the bottom right corner.  If you move your pouse pointer over it, the cursor will change into a "+" sign.  Then drag, and Excel fills the cells automatically.

Other good candidates for auto fill are:

• Months of the year
• Numerical profressions (eg: 3, 5, 7...)
• Text +Numerical progressions (eg: Period 1)