Royal Society of Chemistry podcasts. This time it's about a compound that is familiar from many a chemistry set - copper sulphate (or copper sulfate as the PC police require us to call it). This brilliant blue substance (at least in its hydrated form - pure copper sulfate is practically white) finds its way into a wide range of places from agriculture and book binding to the arts, where it has the honour of taking part in one of the few Turner Prize shortlisted artworks that the general public can actually enjoy. So come on - succumb to blue. You know you want to: take a listen.
The Internet has gone mildly bonkers over a child in America who was marked down in a test because when asked to work out 5x3 by repeated addition he/she used 5+5+5 instead of 3+3+3+3+3. Those who support the teacher say that 5x3 means 'five lots of 3' where the complainants say that 'times' is commutative (reversible) so the distinction is meaningless as 5x3 and 3x5 are indistinguishable. It's certainly true that not all mathematical operations are commutative. I think we are all comfortable that 5-3 is not the same as 3-5. However. This not true of multiplication (of numbers). And so if there is to be any distinction, it has to be in the use of English to interpret the 'x' sign. Unfortunately, even here there is no logical way of coming up with a definitive answer. I suspect most primary school teachers would expands 'times' as 'lots of' as mentioned above. So we get 5 x 3 as '5 lots of 3'. Unfortunately that only wor