4000 words is nothing. Every single assingment I do involves reports of at least 4000 words plus the actualy technical delivery of the product i.e a program.
My main diseratation is going to have to be 10,000 words plus the a deliverable.
4000 is a lot for A level students though. Writing technical reports of 4000 words is also quite easy as its just a matter of reading up on the science and woffeling about it.