This should be simple... if you know how to program for phones, which I don't!
There are several different projects that fall into the category of "Here is something identified as X. X comes in 4 flavors. Which of the 4 flavors is it." In each case, users should see a large version of the image they are identifying, and then example images of the 4 flavors.
In an ideal world, there would be a way to generate these apps easily as new science questions come up.