This is a very small light sensor. A photo resistor (also known as a photodector, or photocell) changes resistance depending on the amount of light it is exposed to.
The H8054 PIR motion detection module provides basic motion detection in a small package. Compatible with the Arduino and Raspberry Pi
The HC-SR501 is a passive infro-red (PIR) sensor which is used to detect motion based on the infrared heat in the surrounding area.
2WD self balancing robot! This kit is a perfect plataform for learning Arduino, PID control, serial communications(Serial, I2C, SPI), PWM signals, IMU filtering, etc.
This is a direct drive 4WD robot kit that uses Nexus mecanum wheels. The mecanum wheels allow it to vector in any direction.