Ted Wragg perpetuates a number of physics myths in his tips on teaching from the Big Picture (TES Friday, July 10).
First, the main reason that astronauts wear helmets and spacesuits is that otherwise, in the vacuum of space, their blood would boil and they would explode due to pressure difference across the body; considerations about air supply and keeping warm, while valid, are secondary.
Second, rockets in space are not "free from Earth's gravitational pull". Indeed, they are very much under its strong influence while they orbit the Earth.
And third, can we be clear that a geostationary satellite does indeed circle the Earth, once every 24 hours? Wragg contradicts himself on this point, by writing that a satellite does not circle the Earth, then later mentioning its orbit - quite apart from making unclear the difference between geostationary, and other types, of satellite.
We must thank Ted Wragg for amusing us and giving us great insight over the years into educational claptrap and ask him if, this once, he will forgive us for pointing out scientific reality - lest an unsuspecting teacher uses his tips in class, and makes the job of us physicists more difficult in future.
Robin Parker Physics teacher The Pastures Stevenage Hertfordshire