20 to 25 percent of American K-12 teachers use social media as a way to become part of a professional community, according to a survey by the U.S. Department of Education. Twitter in particular seems to have caught on with many teachers. Important assets are Twitter's 140-character limit and “hashtag” function, which allows a user to attach to a message a unique identifier code for anyone interested in a particular topic. Twitter also allows teachers to check in when they only have 45 minutes before their next class, for example. When Kevin Jarrett, a computer teacher at Northfield Community School in Atlantic County, N.J., wanted to teach his kindergarten pupils about farms, he sent out a request on Twitter and soon connected with two farmers who answered his students' questions by video. Such educators are among a growing number in the Philadelphia region who are using Twitter, the social-networking and micro-blogging service, to enhance their teaching, often on their own time. Some educators use Twitter – through which users “tweet” messages limited to 140 characters – to connect their students with the outside world. Others use it to share resources and ideas with other teachers. For teachers who spend much of their days as the only adult inside classrooms, Twitter – along with other social-networking websites – can provide a unique platform for conversation. Teachers have traditionally networked through conferences. A drawback from those meetings, said Bill Brannick, principal at Monsignor Bonner and Archbishop Prendergast Catholic High Schools in Drexel Hill, is that once they are over, the connections often disappear. Many educators who use Twitter say it takes a little while to figure out how to make the service work for one's needs. The process involves figuring who somebody might want to follow and how to most effectively send out requests or updates, for example.