I teach middle school and have a good rapport with most but not all of my students. Something I noticed recently has been bothering me. When I come around to check homework, it is not uncommon for a student to show me last week's homework and try and pretend it is this week's homework. Now I'm not stupid so it's easy for me to figure this out with a closer look -- and I DO take a closer look, and then say something like "Oops, this is last week's homework. Did you do this week's?" The student would then go "Yessss ...." but will magically then be unable to find it. It is clear that they were trying to trick me into accepting last week's homework. This has happened with several students and each time they kind of giggle with their friends and do not act remorseful -- more like "darn it guys, I was caught." To each of them I've only said "It's one thing not to do your homework, but it's another thing to lie about it" and then just moved on. However the lying really bothers me. The hw isn't even that many points so it seems like they're lying just for the heck of it. It's disappointing and I don't like to see my students acting this way. How can I reinforce the importance of honesty and integrity in my classroom?