Tips for Science grading?

I found that breaking it down into smaller, manageable groups works best.

I totally agree with this! In my classroom, we always start with a mini-lesson.

There's a really good website that covers this (TeachersPayTeachers has some free ones).

It really depends on the grade level, but generally I find strict boundaries help.

Make sure you document everything in case administration asks.

Have you asked the principal for extra budget for this?