For this activity you will need an NXT brick, a wire, an NXT proximity sensor, and computers running MINDSTORMS

1. Have student design an alarm box that will detect when a person approaches the box. If students want to use more than one proximity sensor or a different sensor as well they should be allowed to be creative.
2. Allow students to decide how their security system will respond when someone approaches (display something on the screen, make a noise, drive away)
3. Have students program the NXT to respond when someone approaches the proximity sensor and to stop responding when that person backs off.
1. The entire program will need to be looped so that the NXT is always secure
2. When the NXT is not being threated it should signal that it is alarmed by displaying "system alarmed" on the NXT screen.
3. When the proximity sensor senses that an object is near it should respond (say by displaying back off! and playing a tone).
4. The alarm should be looped until the proximity sensor no longer detects an object close to it.
4. Students may use more than one sensor to trigger the alarm.
5. Allow students to test and redesign their prototypes.