I like the way you have set up the plan for teaching about moles. You have some type of mixed classroom and students are not all working on the same subject. Since you have a lot of independent learning, the technology is a great way to introduce the subject. The videos would be an excellent way to show the students how to do the calculations and show them the amount of substance you are calculating. Your stair project is a nice piece for this lesson. If you add a video, the learning experience would help all types of learners. Some need to hear about it, some need to see it, and some need to read it. Your lesson would acomplish all of these needs with the video accomponied by your stair.
For the socialization aspect, if you had some students in class working on chemistry, they could work together to calculate some problems then collaborate on some questions about the process. My other suggestion would be to have some type of discussion board on a Wiki that the students could have some discissons on about the caculation of moles and what it means.