Twiddla is a awesome FREE whiteboard tool. It allows you to create an on-line place for you and your students to collaborate.
In the space you can use the drawing tools to mark up the blank whiteboard or upload a document or image to annotate...
To have others join your session, they merely need to point their browser to the URL of the session you created.
The REALLY great part is that this tool works on Mac OS, Win OS, Chromebooks, iOS and Android devices.
NOTE -- sometimes it is more difficult to participate from a tablet or smartphone just because of the screen real estate...
This tool can be used in a variety of classroom activities...
Upload a map to the whiteboard, have students in groups markup the map features: identify mountain ranges, color certain features a certain color, etc.
Upload a document and have students correct the document: capitalization, spelling, punctuation, etc OR diagram parts of speech.
Use the whiteboard to have students draw an array and then have other students write the repetitive addition sentences possible from the array.
This is a FUN and ENGAGING web 2.0 tool for the elementary through middle school classroom!
Try Twiddla today!