>> "It's definitely the most popular network amongst teens in my (UK) school."
I'm not sure I'd put to much weight on that. From my personal use and what I've seen people seem to spend longer periods of time on Facebook. Whereas Snapchat requires seconds at a time. When you're asking who used something before school you have to remember these kids likely got out of bed, didn't have time to shower and ran to the bus :) I'd love it if you had also asked about what they did after school the previous day. Of course my evidence isn't very robust either but I don't think you can draw your conclusion from that survey.
I'm not sure I'd put to much weight on that. From my personal use and what I've seen people seem to spend longer periods of time on Facebook. Whereas Snapchat requires seconds at a time. When you're asking who used something before school you have to remember these kids likely got out of bed, didn't have time to shower and ran to the bus :) I'd love it if you had also asked about what they did after school the previous day. Of course my evidence isn't very robust either but I don't think you can draw your conclusion from that survey.