Fortunately, we have compasses to give to professor Lidenbrock. You have made some compasses, so the journey is going on. Here you have one picture with some of your compasses. You can see that all of them work correctly, all of them point to the North.
By the way! What have you learn about magnetism? How does a compass work? Why is there a magnetic field in the Earth?
Don't worry!!! These are difficult questions for students of the first course of ESO. But that the study of magnetism has been very important to know the inner Earth structure. Try to answer them. You know... extra points to travel to the centre of the Earth.