Returning your classroom kits is just an option, however it really helps our circulating inventory! You can still check out a complete kit without returning your current kits. For most teachers checking out science kits saves time and money from having to refurbish them from the classroom. As a reminder, we only replace consumable items for kits that remain at schools and not the components. By checking out circulating kits they will always come fully stocked at no cost to schools even for lost or damaged materials. We have also added new 2nd edition teacher guides to our science kits which is a nice upgrade.