Repair the "play habitat."
Many of the toys available for children now are what Christakis calls "gizmos," or, toys that really only do one thing — but if a child is handed something more open-ended, like blocks, they're forced to make cognitive leaps. For example, if a child has a toy cell phone, they know the toy's purpose is to be a phone. If a child is handed blocks, which can be used to build any number of things, and they put one to their ear as a phone, they're making a symbolic connection between a block and a real thing.
To restore this type of open-ended play, we can help our children to think outside the box when playing with simpler objects. Rather than play solely with "gizmos," we can ask kids, "Do you think we could make a car out of some of the things we find in the kitchen?"