In a world that is constantly revising its knowledge base and at an ever-increasing rate, traditional methods of learning are no longer enough. For teachers, who often have limited opportunities for collaboration and sharing (particularly at the same grade level or subject area), professional growth can be more of a challenge. That's where a Personal Learning Network (PLN) comes into play. Here are some tech tools that can help teachers build their PLN:

Google Reader:Takes blogs and other sites with RSS feeds, and automatically posts any updates from these sites and places them in your Google Reader page.

The iPad is a wonderful place to read such updates. Check out Reeder (available for Mac and iPad), Feedly, Mobile RSS (free and paid iPad versions)

Twitter - This can be a great resource, particularly for the most up-to-date ideas, news, and information. Follow educators who post helpful ideas or links. Search by subject or hash tag (some good ones listed here with explanations). Can be a great place to discuss and share ideas. #edchat, happening on Tuesdays at noon and 7 pm EST, discusses participant-selected educational topics.

Delicious and Diigo - Search for and share bookmarked resources. Access your saved bookmarks, wherever you go.

Social Networking tools such as Edmodo, Facebook, and Google Plus. Follow individual people or join an organization's page (by clicking 'like")