As hard as it has always been for some of my students to understand, the parties are not part of government.
Your students? Really? Not a part of the government. Really? I must be imagining the government promoting those two parties during tax time.
I mean... They CALL it something that doesn't refer directly to them. But the money goes to the two parties. Third parties CAN get some of it, a much smaller portion.
I think you need to do more research to fully teach your students just what's going on. Unless of course... It's not really about teaching them.