Doo-dahs are a wonderful way to bring information into a classroom discussion in a controlled manner. A Doo-Dah can contain text, annotations or images, even those added or created on the fly. A picture is worth a thousand words, so download the file and have a play. You will soon learn the power of doodahs!

If you have group competitions in your class, this is a neat way to keep a running score (up to a maximum of 30 points per team).

A wonderful collection of clocks. The time comes from your computer's system clock, so if that is correct, these clocks are as well.

Five 10-second timers, each of which culminates in a bomb. And you can even have more timers if you wish by first choosing 'Disable Actions' in the upper right corner and copying and pasting one of the bombs.

This ActivBoard flipchart keeps the scores for up to six competing teams.

A 60 second timer with a difference!

A sure-fire way of getting your students' attention in 10 seconds.

This is a worksheet on Fermi Problems that I created back in 2005.

Type in a length and a unit, and this website will convert your boring old unit to something much more interesting, eg 200 cm converts to 39 AA batteries end to end, or 10 five month old human fetuses end to end or even 1.4 standard railway gauges. Fun and educational. Three thumbs up!

http://www.sensibleunits.com/

Not an interactive digital resource, but a very useful resource for teaching conics nonetheless. From Lou Talman.

http://clem.mscd.edu/~talmanl/PDFs/Misc/APCalculus/ConicGraphPaper.pdf