This interactive whiteboard resource is intentionally fast paced to encourage students to estimate and consider what answer looks correct without necessarily working it out accurately. The fast pace also ensures a number of students can have a turn at the front of the class without taking up to much time. Class questioning could consider what ways we can check whether an answer looks right. I.e. adding 2 odd numbers will produce an even answer, rounding to the nearest ten and then adding for an estimated answer etc.
Borrowing the idea of diffusing a bomb from television drama the students need to connect the components together based on the addition questions and answers. Click and drag from the question to the answer (or vice-versa). Every failed connection results in sparks and a 5 second time penalty so accuracy is important.
This resource has sound so ensure your speakers are at an appropriate level.
As always if you encounter any bugs or problems please report it here. If you like this resource and would like it applied to another concept or have a suggestion to improve it also leave your comment.