Concrete Form Gap Question
 

I'm going to be pouring a 8.5' x 16' concrete slab. I've dug up the yard and flattened it out fairly well. I built the form out of 2x4's and used 2x2's posts every few feet for anchoring it. In order to make the form level, it has some gaps underneath the 2x4's.

What is the best way to fill in the gaps under the 2x4 form?

Thanks!

you've nail'd the form to the stakes,,,
 

right ?,,, use some dirt to fill under the forms,,, just stomp it tight so it won't slide out from the mud's pressure.