Tests are a form of distinguishing the difference between students and therefore gain a general understanding of how students perform, both as a collective and individually. With the results, teachers can suit and format curriculum and therefore suit their teaching to help best support a student's weakness and improve it.
They are important because teachers can tell if the student is paying attention or not and understanding the subject. Also, so the teacher can help the student in what they're having trouble with instead of going everything all over again. They can also help the teacher if a certain student is having trouble or not.
Tests are very important for students. Tests are a great way to ascertain what a student has learned about a particular subject. Without tests, children and students would never have to apply what hey have learned in the classroom. Tests help measure how a student has done compared to other students in the class.
Tests are very important for students. I do not think they should be graded harshly while taking a test but I do believe it helps them know what they have learned and better understand how they are doing. Unless you know what you have down and don't it would be hard to study and further improve on the right aspects.
Tests aren't important because in most cases they are used to measure a teachers success at teaching students. It can't be measured accurately because some students don't really care about grades and what they are learning and some do which results in a wide variation of test results that can hurt a teacher.