Have you ever assembled a toy, a model airplane, a piece of furniture, or anything else for that matter by relying exclusively on text instructions? How did it go? Was it as easy as advertised? Any chance those directions referred to parts and pieces that you'd never heard of? How desperate were you for a picture or diagram or video showing you what to do?

Now, imagine if, as a teacher, all you did was ask your students to open their books and read pages upon pages of text. First, would they even be able to decode all the words? And even if so, how well do you think your students would understand new concepts they encountered? And for how long and under what circumstances would they remember those concepts?

Of course, we know that you …