http://www.preschoolpalace.org/Curriculum.html
I have used this curriculum and it costs maybe $10 but is very comprehensive. Some activities are better for older children or groups but can easily be modified to a younger age. I usually choose one or two activities to do daily with my group which is about the same age as yours. It is repetitive too which helps build skill and knowledge. It gives me a good starting point and ideas all in one place on different themes, rather than hunting around endlessly on the web! Also comes with lots of printable handouts and worksheets for practicing skills when they are a bit older and can do pencil work.