One of the great things about the metric system of measurement is that is based on the powers of 10 which means that all we have to do when converting between different units is to move the decimal point. The following diagram can be used to help convert between the common metric units.
Moving up a step moves the decimal one place to the left where as moving down a step moves the decimal one place to the right.
Teaching students about the Sieve of Eratosthenes can help them understand how prime numbers work. Many students may watch a teacher of video clip about how to create a sieve but are unable to do it on their own. I've created several Moodle cloze questions that can help students try it out on their own and get immediate feedback. The image at the right shows what the sieve question looks like. 
