The Apple App Store and Google Play are chocked-full of educational apps for your kids, some excellent and some schlock. Separating the wheat from the chaff is no small task; thankfullyGraphite (a spin-off from Common Sense Media) does an excellent job highlighting and reviewing the better ones. This list from Education Next is super-helpful too.

But in both cases, the focus is overwhelmingly on apps that teaching reading, writing, and arithmetic. Maybe because that’s what schools are most focused on, or maybe those subjects present fewer design challenges for app builders.

But that leaves a gaping hole: The teaching of history, geography, science, art, and music, what you might otherwise call “content knowledge.”

This is a big problem for three reasons:

1. Those subjects are important in their own right;
2. They are treated as after-thoughts by most elementary schools, making them even more critical to cover in out-of-school time;
3. They are essential if kids are going to actually learn how to read.

That last point is worth lingering on. As E.D. Hirsch, Jr. has argued for thirty years—and cognitive scientists have since proven in the research lab—teaching content is essential to teaching reading. While it’s important for children to learn to decode the English alphabet, they also have to grow their vocabularies and background knowledge. Those two things are intimately intertwined and closely correlated with broad knowledge of the world.

The ability to pick up any text and make sense of it depends in large part on knowing at least something about the subject matter. A book about Tyrannosaurus Rex won’t make much sense to a boy who’s never been to a museum to see dinosaur bones, even if he can spell out the words. A book about Harriet Tubman won’t make much sense to a girl who’s never learned about slavery, even if she knows how to decode.

So if your son or daughter can sound out words (or even if he or she is still working on it), you need to see building knowledge too as an essential, non-negotiable component of building literacy. I’ve long argued that high-quality educational TV can help. So too can the right apps. Here are some you might consider. (Have other suggestions? Post them to the comments section. And thanks to Fordham intern Kate Stringer for curating this list.)

History

Geography

Science

Art

Music