I believe that it is important for us as religious educators to challenge our students to thinks about such matters. We need to invite our students to have such a faith. With proper adaptation and questions suited for the age level, it could certaily be done in younger grades. Ask the students who drew them to say a few words about the structure of their church. Use the pictures of churches, cathedrals, basilicas you have found to broaden the scope of the process.
Web site provides pictures of several types of architectural features in churches.
My Christianity and Architecture page links to 26 virtual tours of Cathedrals and Basilicas as well as to other useful sites on church architecture. Sacred Place , part of the Passionist Research Center Website, gives a description in photos and text of 9 beautiful churches. Provide the students with a glossary of terms relating to church architecture. Use could also use the floor plan linked to the image above. Ask them to justify in writing why they would make these changes.