Por si algún profe quiere investigar sobre estas 70 apps y ver si le son de utlidad. Yo uso algunas // The 70 Best Apps For Teachers And Students - Edudemic. These are listed as itunes apps, but I'm sure a lot of them can be found for Android as well.
Had when i worked in a preschool and kids love them! I would use colored sand instead of white salt. DIY salt tray with alphabet cards. Easy to make and kids have fun smoothing out the salt after correctly making the letter