OK, now I don't take most of my tamas to school w/ me because I lost one of mine when it fell out of my hoodie pocket and I never got it back. I only take my mini and my connections *rarely* to connect w/ my friends.
What I do (or did recently *eek Cake needed food* before I lost mine) is I keep them in a pocket, not pausing them (usually) and checking and playing with them during recess, lunch, math, science, art and occisionally LA. In gym I have to suit up and can't look at them (so I usually pause 'em), in SS I have just checked.played w/ them @ lunch.
Note: some teachers could care less unless they make noise or you mess with them during a lesson. My math teacher saw me feeding my mini when I was at a fieldtrip watching a movie and he scolded the class about our lack of atteniveness using me (but not saying my name) as an example, but didn't take it away. People really do think it a fashion acessory/clock! (this was a mini though, not a connection.
And of course, If you have a special (jap, old, etc etc) tama, don't bring it to school. Tama theives may take them.