It is important to be aware of today's limits of AR technologies in the design phase so to avoid to generate unrealistic expectations and consequent disappointment.
Very high-end, and therefore expensive, smartphones and tablets are required.
The lack of uniformity in the behavior of Android devices makes very difficult to control the quality of experiences for these systems.
Battery life is still a big problem. An experience that is continuously active runs out of battery generally within a maximum of 1 hour.
It is still very difficult to make different users interact within the same experience.
The market is still very immature and the chances that a product or platform will not last are very high.
Keeping these limitations in mind, today it is more than possible to create reliable solutions for controlled environments, as those in schools tipically are.