This document summarizes an active learning assignment on infrared sensors. It introduces the topic, explaining that IR sensors are used to detect obstacles like human vision. It then describes the basic components of an IR sensor including the IR LED transmitter, photodiode receiver, and comparator circuitry. The document explains that the IR LED transmits light which bounces off objects and is detected by the photodiode, with the output compared to a reference voltage. Finally, it outlines some common applications of IR sensors and their pros and cons.