"I'm applying for LPN jobs so won't have to make plans of care, but will do first aid and help with screenings. "
Are you an RN? If so, you are responsible for care planning under many of the state nurse practice acts even if it is not in your job description. You will need to check on that. In order to not have RN accountability, you have to let your RN license go inactive, but then you would not qualify for the LPN jobs as you will have no license.
"Which books might help most on assessment and course of action for school-age kids?"
The best book for that is:
Individualized healthcare plans for the school nurse. C. Silkworth, M. Arnold, J. Harrigan, & D. Zaiger (Eds). North Branch, MN: Sunrise River Press
There is also:
Selekman, J. (2006). School Nursing: A Comprehensive Text. Philadelphia : F.A. Davis Publishing. http://www.nasn.org
NASN also recommends Well Child Assessment for Primary Care Providers. Margaret R. Colyar, DSN, ARPN, C-FNP/C-PNP, University of Utah, Salt Lake City, Utah. http://www.nasn.org