Students make various types of mistakes in their language learning including slips, errors, and attempts. When assessing student performance, teachers provide both explicit and implicit feedback through praise, comments, grades, and reports. During oral work, it is best to correct mistakes as late as possible and feedback should be personalized. When providing written feedback, teachers should ensure it is legible, focuses on important aspects, uses a positive tone, and gives a manageable amount of constructive criticism and praise. Feedback should also be timely, use helpful styles and correction symbols, and consider the student perspective.