How bad is your Cold. If it is Severe,the Best suggestion is to go see a doctor and Stay Home and watch Movies, If you could, Drink Water And Sleep Lots. If it is A little cough then stay indoors And Keep Warm
Actually: YES it is bad news. Murphy's Law of cussedness guarantees that you will have missed something very important while you were ill. Make a point of asking your teachers what lessons you missed and get the notes where possible so you can catch up. I remember being away on the day they taught the Electrochemical Replacement series (?) and it took me a month to get back up to speed with the rest of the class.
I graduated first in my class with a 4.0 GPA and valordictorian - and I found every reason under the sun to stay home - until the school threatened not to graduate me if I didn't meet State requirements (it was a private school) - I learned to homeschool myself - but at the time - there was no such thing. You should go to class - stay out only of you're sick or you got hit by a bus. School teaches you more than just the lessons - you learn to interact with other students - socialize.