I tell you another thing, it's a lot of hard work

for any given unit you creat you may need to create many different versions of it to aim at many different levels of students... even within the same class the abilities of your students can range enormously and it's your job to get that unit accross to all of them, especially in primary school, I have had to create 3 different versions of the same unit to teach to one class as the students within that class were at such different levels of development

like who have you always imagined created the work your teacher gave you? LOL not the brightest spark there are we Tim?