www.readwritethink.org/professional-development/strategy-guides/exit-slips-30760.html

Exit slips invite students to briefly reflect on what they learned during a lesson and can provide teachers with an informal assessment of student understanding. They can help teachers find out how students are synthesizing and connecting what they are learning, what they are still wondering about, or any other information that can assist in planning further instruction. A variety of practical suggestions for employing this versatile strategy are provided, along with sample prompts.