science curriculum recommendations

Ok, all.  I have a question.  This fall I will have a 5.5 yr old and a 9.5 yr old.  I was going to use 106 Days of Creation with both of them.  Would it be better to wait until the following year?  If so, what would be a good thing to use?  Right now we are reading Outdoor Secrets and Among the Meadow People.  We were doing HOD Preparing science but we found it very boring.  So far just reading nature books seems to interest them.  But I’d like to go outisde of “nature” (bugs, animals, etc) with my son (now 8.5) soon.  However, I want to keep them together.