If you develop poor study habits, you will be your own worst enemy. Important information is often given in the first or last few minutes of a lecture period. There is usually a good correlation between attendance and good grades. While attendance alone will not guarantee a final grade of A, poor attendance will almost certainly result in not receiving one. Such excuses are usually the result of poor planning.
Professors usually give students a syllabus at the beginning of the semester.
The syllabus should contain the dates that papers are due and the days that examinations will be given. Aside from illness, there is little excuse for not being prepared the day of an exam, or for not having a paper completed prior to the deadline for its submission. You would receive these materials if your instructor did not believe them to be important. This will familiarize you with the terms, concepts, phenomena, etc, which will be discussed in lecture. Note carefully all bold faced or italicized words.