This is a good educational kit, but can also be used in a practical application.
There are many types of sensors used in alarm systems. This kit will demonstrate three different kinds. One is the infrared "break-beam" sensor using a laser diode module and a photocell.
Another type is the magnetic proximity sensor usually found protecting doors or windows. A magnet is embedded in the top part of the door while the magnetic sensor is embedded in the door jam. When the door opens, the magnets are pulled apart and the alarm is tripped. This is a good sensor because it is nearly impossible to fool or disable the sensor. Also known as a Hall Effect sensor.
The third sensor is a force sensitive resistor (touch sensor). It can be used to detect something stepping on it, or it can be triggered when a weight is removed. All three sensors will be integrated with an Arduino microcontroller. For practical purposes, this project will be built around a breadboard, but this can certainly be integrated into a real life project. Protect your crown jewels!