Check out these "Cube Conversations" from Steve Wyborney. In short, he provides images of cube structures and ask students how many cubes are in the structure. The downloadable printable sheets allow students to describe how they "see" the structure. I suggest you watch the 8 minute video to see how he approaches these problems to engage in rich mathematical discourse with students. He uses a Powerpoint presentation to show the slides, but you can simulate them without the Powerpoint.