Platform Choice:
Facebook allows for you to build groups. Not to be confused, a page and a group are different. This article does a great job at explaining the difference. A page is just a profile but for a company or thing rather then an indviual. A group allows interaction between users who join. In the context of a classroom, setting up a Facebook Page allows you to share info and students/parents read or you can create a Facebook group. This allows students to join and discuss.
Twitter is another popular choice when it comes to education. Twitter is great as you can quickly Tweet what your class did for the day or within a specific lesson. Just there is a character limit so it might not be useful to everyone. Students who are absent are able to catch up. Parents can follow and see all sorts of cool initiatives happening within the class. From first hand experience, school wide Twitter accounts are popular and very useful. Students feel like there is a community and they want to do things to contribute.
Blogger / Google Sites is another really great tool. You are able to add images and write longer pieces of information then something like Twitter allows. Students and parents can both follow the blog or site, and depending on the site settings (that you decide), they can add comments.
Messaging apps are social, right? I have also first hand experience using messaging apps with group chats for the class. Everyone is able to participate within the chat. Apps like Hangouts (which is built into Google for Education suite) is an example that you can utilize within your classroom.
Advantages:
Social Interactions is a really neat website that aggregates "opportunities to make a difference from over 50 online platforms". I think this is a great example as to how you can use social media to connect people to make a positive impact.
Instant information and feedback from others around the world. This is a great way to connect with professionals and have virtual field trips anywhere providing students with a more real life, hands on lesson.
Digital portfolios like LinkedIn allow students to not only build portfolios but also allow connections to professionals to learn more about careers. According to this survey, 90% of people think LinkedIn is a useful website.
Disadvantages:
For starters, any student under the age of 13 should not have accounts as per the standard policy. This means social media will only work for students in grade 8 or older. If you plan to use it with younger grades, consider something like Blogger or Twitter where students and parents are able to follow along without accounts. This also means no real interaction online.
Data Collection makes website and app approval slow. You need to be careful on data that websites collect, hence why schools boards opt for an "approved" whitelist of websites and apps that are safe for the students to use. Data collection and giving up privacy is a huge issue and is amplified when using social media. Facebook for example has a long history of data problems. This is not ideal for student access.
OCT Professional Advisory: Social Media :