If you miss class, you may schedule a make-up lab with me via e-mail for the following week. I am available during the 4th class hours. Some labs can be completed at home and won't require this.
Yes, it is important that you retain the information that you have learned. Many students becme adept at memorizing the material for a short time and then promptly forget it.
I will not rule out the possiblity of extra credit, however the students track record will factor greatly in to this option. If a student is turning in all thier work on time and really tying and is just a little short, I may allow extra credit. However if a student is consistenly not turning in work on time and has not diligently done thier work more than likely I would not allow them extra credit - they should concentrate on getting the required work done and done well.