I found the Earth School curriculum on etsy and I really like it. Of course you'll probably have to change it up to suit your needs, but it has a good foundation and great hands on ideas. It was originally created by a ECE who was homeschooling her kids.
And each package is usually around $20 (you buy each "unit" separately), so it's not a huge investment if you just want to check it out. I'm using the arctic one now, 5 senses next.