Some people might argue that the most important and only factor in grading should be examinations, because they believe it is only way to assess someone about the particular lesson, but I disagree with this idea. I think that class participation is an essential way in grading because it enables students to participate in class discussions, ask the teacher unclear points and help them socialize better.
First, high participation lets students develop themselves in group discussion. For example, when students take part in a discussion, such as the one about evolution theory by Darwin, they come up with several clashing ideas with each other. This discussions do not only help them grasp the certain topic more comprehensively, but also teach them how to stand for their idea in a group talk. While one student might points out the weakest side of the theory, the other student might try to debunk that idea. In sum, practicing beneficial group discussion is only achieved by high participation. That is why, grading should be based on participation rate for each student.
Second, the students can ask the points that they can not understand during the lesson. For instance, when a student has a problem solving the a math problem, he needs an assistance to solve this problem. Considering the facts that most of the time parents are too busy or unfamiliar to these kind of math problems, it is only the teacher who can help the student with this math problems. In addition, students can ask the point they can not understand during the lesson while the teacher tells the lesson, so that the students can get the answer right at the moment when the problem occurs, therefore the lesson would be more beneficial to students. In other words, the grading should be based on class participation to encourage students to listen to the lesson at the classroom and give them a chance to ask questions during the class to grasp the topic better.
Third, school is much more than grades. We do not only learn academic stuff at schools, we also learn how to socialize. Students come together at cafe or somewhere to talk about their problems. They understand the importance of friendship in this way. Moreover, they gain self confidence. Since we, humans, are social beings, we need to be appreciated by others. Classroom environment which is teem with peers in the similar ages provides the chance to interact with others and consequently students develop self esteem from these interactions. Therefore, compulsory class attendance will let it possible for students to improve their social side and self esteem.
After all is said and done, I think the class attendance is much more important than the mere test scores. Students can appreciate the importance of the social life and learn the lesson better asking questions any time during the lecture. In addition, group discussion can enhance their edge in expressing their ideas. Therefore, we all should be favor of supporting the idea that that assessment should be relied on the class participation solely for producing high caliber students.