For tips on communicating science to kids, the Center on the Developing Child at Harvard University has some guidance: https://developingchild.harvard.edu/collective-change/communicating-the-science/
I highly recommend the Online Writing Lab (OWL) at Purdue website for help with APA style, and other citation styles. The APA Formatting and Style Guide (7th edition) provides examples of in-text citations, reference lists, and other helpful information.