I prefer upper school when relief teaching but some times (and it only happens if its absolute emergency) I have to cover a younger class. So I was looking for a resource site and I came across this one.
It has a few upper school resources but it really is targeted towards younger kids. It is called Have Fun Teaching and they heaps and heaps of free resources for lower school. These include worksheets, posters, classroom templates, songs, maths and language sheets. Far too much to mention here but CLICK HERE if you want to check it out.