I think social media in the classroom is a great way to keep kids connected in ways they are (most likely) already using. Facebook and Twitter can be useful tools when used in meaningful ways. Facebook allows teachers and students to stay connected in groups to share information, assignments, and resources. Its forum-like abilities means that students can engage in meaningful conversation and respond to each other. Twitter can help students get and share small bites of information and follow hashtags that help network them with others discussing the same topic all over the world, including following current news and world events in real time, as they unfold.
Most students are already using Facebook and Twitter to stay up-to-date on everything else going on in their lives; having access to their classmates and teacher in an environment they're already comfortable using to continue the classroom conversation, get assignment reminders and ask questions 24/7 of other classroom members helps kids feel connected and means they are more likely to be involved and engaged in their learning. Those online conversations and interactions helps students to continue thinking about class topics even when they're not in class, and encourages them to participate anytime, anywhere.
While there are a lot of pros to the idea of using social media in education, (with students 13 or older, the minimum age to create accounts on these networks) some groundwork needs to be laid in advance and expectations covered to address the "cons." Students need to be reminded that even when at home, they still must be respectful in these online spaces with their peers, as it is an extension of the classroom environment. (This can go hand-in-hand with digital citizenship lessons!) Teachers should create a separate, professional account to use in these situations as well, instead of friending students on their personal accounts. While some may think that students will use these networks inappropriately, or that allowing them to use Facebook and Twitter in class means they will spend class time using these networks for personal reasons, it's all about setting those expectations of access and use with students ahead of time, and outlining when and what is appropriate. When you integrate the use of these social networks in meaningful ways as part of their learning, you'll find that students WANT to engage in the assignments, because they're excited to be able to use the social networks they're already comfortable using in an educational way. Most students are already learning and exploring about world events and news from others through their social networks, so it'll be a natural extension that can encourage this desire to always keep exploring and learning.
When used appropriately, social networks in the classroom can provide rich and meaningful experiences that students are comfortable with and can relate to, encouraging classroom participation and conversation even when they're not in the classroom.