Touchscreen interfaces would be easier to use if we designed them with finger paints. We stop “designing” this way the day we graduate from kindergarten, but think about it. Can you be sure a button will be large enough for a user to push? Will her hand cover up anything important? We wouldn’t need to ask questions like these if we had designed the touchscreen with finger paints. It would be self-evident.

Of course, we don’t design with finger paints… but we do still have fingers. Put your hands up to truly test your interface design. The earlier in the design process the better. Pay special attention if your hand would obscure the results of touching a button — menus, status bar changes, page redraws, etc. Major action buttons are best placed at the bottom of the screen, with their results positioned directly above the point of action.

It must be true. Everything you need to know, you really did learn in kindergarten.