Pathway: Safe Cracking

Scenario: Nebraska Public Power District has acquired several top secret power pellets and must protect them until they can be utilized to produce electricity. We have assembled our best electrical engineers to build safes to keep potential crooks at bay. Your job is to design a prototype to help us keep our top secret power pellets safe.

1. The safe must have at least one alarm. An alarm is any electric circuit that turns a light on or off or sets off a buzzer. The alarm must be electrical and not a “mechanical lock”.

2. Your safe must have a light on visible through the peep hole at all times (unless it is your alarm and the Thieves turn it off).

3. Your safe must have a solution that you can demonstrate successfully. If you require tools to open your safe those tools must be made available to the thieves.

4. Your power supply is one 9-volt battery. Please take care of your energy – if you waste it your alarms will not work.

5. Your solution cannot include disconnecting wires – if we allow this then the thieves could just wiggle wires until the alarms don’t work. It is acceptable to position wires that will touch when something moves and then simply push them out of the way for your solution.

You will have plenty of build time to create your safe. Start with one alarm and then add more. Be creative, there are many types of switches that can serve your alarms well. Take care to keep all wires attached – the biggest downfall to your safe will be loose wires. When it is time to crack your safe you will follow these steps:

1. Your team will set up your safe with the power pellet inside – be sure that your internal light is on.


2. The team of thieves will then have four minutes to open your safe and remove the power pellet. If no alarms are set off the thieves win.


3. You will also have a chance to be a team of thieves.

You have done a great job engineering your safe. Now it is time to write the instructions for opening the safe without setting off the alarm. You need to follow the example given - right down to the smallest details - to write a Work Order Procedure.

Safe cracking can be done with a variety of supplies from your "junk drawer!" This list is just a recommendation you can adapt the list as necessary. Avoid giving students pre-made switches - that takes out all of the creativity. Limit the supplies to make things harder for varying levels (especially the amount of electrical wire you allow). 


THE BOX: you can use a simple shoe box with one 1.5" hole cut in one side or you can use the peg board box idea where you give students a deconstructed box that they can assemble with zip ties. You can set the dimensions of your box but want it similar in size to the shoebox.



• 9v Battery

• (3) Christmas Lights

• (2) Aligator Clips

• Electrical Tape

• Clothes Pins

• (2) 12” 22-guage wire

• Craft Sticks

• 12” x 12” Aluminum Foil

• Orange Wire Nuts

• 12” String

• Rubber Bands

• Small Washers

• Small Nails

• Zip Ties

• 9v Motor

• Piezo Buzzer

• Binder Clip

• Ball Bearings

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