Some people are very lucky and they manage to do things at their first attempt. Most of us are not that lucky, but that doesn’t mean that we should stop trying. You may never be the best in the class no matter how hard you try, but the important thing is that you will be better than when you started. Always try your best and nobody can ask more of you than that.
Your teacher will be able to see that you are doing your best, and he or she will be proud of you for it.