This disclosure contains one technology and two devices. (1) Technology We invented a simple method to align graphene or graphite flakes into macroscopic order. Specifically, we used a magnetic field. This has never been achieved for graphene or graphite flakes. Previously, people had to decorate flakes with magnetic nanoparticles, but these nanoparticles are not only useless for device operations, they can further create unintended consequences. Graphene/graphite has numerous applications, this technique will find applications whereever graphene or graphite is used. (2) Two graphene-based devices We also demonstrated two devices: one for magnetic sensing, the other is a graphene magnetic writing/display board.