In recent times, though there has been a proliferation of Web 2.0 collaborative tools that have the potential for full class interaction. My favourite at the moment is Padlet.
Formerly known as WallWisher, Padlet started out as an online pinboard where unlimited users could post notes on topics being discussed en masse.
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Using Padlet (f.k.a. WallWisher) across the curriculum - 2 views
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Free Technology for Teachers: Wallwisher & Google Docs as Online KWL Charts - 3 views
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