Here is a wonderful interactive image created on Thinglink by J Beam featuring some important tools that support the 21st century thinking. As you can see from the graphic below, there are four main skills associated with the 21st century thinking these are : creating, collaborating, communicating, and critical thinking.
Thinglink is fast becoming a favorite tool. This example is great for those PLT discussions. It contains links to tools that can be used to highlight particular 21st century skills.