This is a story related achievement which will unlock with natural story progression.
After unlock the jar make your way over to the students desk, you need to open desk number 6. Inside you will find a magnetic puzzle. This puzzle is fairly simple, but take your time so you don't hit the edges.
You need to move the lock pick from the opposing corner to the corner your magnet starts. The pattern you will be follow is as follows:
1. Move the lock pick up to the first gap,
2. Move as far left as possible,
3. Move up,
4. Move to the far left,
5. Your final move will be to move the lock pick up to the starting point of the magnet.
After completing this you will have moved the lock pick up into the top left hand corner.