CSF Software products, run by Chris Farmer, a Mathematics teacher, has created a Countdown Numbers Game generator, a standalone program, which runs in full screen mode, for use with IWBs. You can go through the "I'll have one from the top, 2 from the bottom and 3 from the middle" routine if you like, before setting the tool to generate the target number, which sets the timer in motion, with background music from the show that makes for that touch of realism. The number range to be used and time scale for activities, can be changed by the user, though the music will only kick in for the last 30 seconds. This however could act as a reminder of task deadlines, and support pace within the session.
You will need to play with this tool before using it with your students, and change the number ranges used to match the needs of the class. The outcomes generated by the students, will no doubt provide fantastic and relevant contexts for mathematical discussion, which I feel is one of the keys to successful Interactive whiteboard use in any lesson. I think the ideal way to organise use of this resource initially with a whole class, might be through "pair and share." Using small dry wipe whiteboards I would encourage students to work together, to solve the problems, before bringing them back together as a class to share solutions, and maybe include an intermediate task, where students take turns within the pair to work on problems, and then check the accuracy of each other's workings before sharing. As in the TV quiz, I would look for the nearest solution to the target number, and not necesarily focus on reaching it exactly, though this would provide opportunities to differentiate the task and extend the more able students. Alternatively use of individual whiteboards, would engage all children in the activity during Oral Mental Sessions.
Use with a laptop in small groups situations, could be a fun way to provide context for formative assessment, and open a window into how students engage with calculation and the strategies they use. Within my classroom I have been concerned that numeracy hours should enable students to develop and extend their understanding of mathematical language through thinking together, inorder to develop shared understanding of terms in context, this tool as a frame for this has enormous potential.
Also on Chris's site are other tools, such as the "Who Wants To Be a Millionaire?" game which I am flagging here as a reminder to pop back and have a look at later. I mention it here though as it reminded me of a strategy I regularly use with my students when they get stuck. Using the IWB children are sometimes so keen and excited to have a go, they either forget or have not thought through their response to a task. Rather than send the children back to their place and ask another child to do the task, which could deflate their enthusiasm, I often ask the child if they would like to "phone a friend" to come and help. This way the child who has come to engage with the board, still carries out the task, but with the support of someone they feel can help them, and both can have their engagement with the task celebrated.