One of our teachers made Gak for the classroom, and once the children were losing interest he added something so simple. Glass tiles!!! This is a great way to not only allow children the opportunity to create and manipulate different mosaics but it also offers a sensory opportunity as well. The cold glass tiles are easily pressed into the Gak leaving an impression. They can also be hidden inside the Gak for others to find. Seems so simple yet every time I turn around there is always children at this particular activity.