The official Science Olympiad website: www.soinc.org
The Science Olympiad student center: scioly.org This site has past tests, information on events, and an image gallery.
Note: Most of the resources on official SO site and scioly are for Division B (Middle School ) & Division C (High School). They can still be helpful for Division A (Elementary School).
NS Science Olympiad website: https://ncscienceolympiad.ncsu.edu/resources/
Informative slide show made by the Medina County Park District
Use phrase "Science Olympiad Rubber Band Catapult" in preferred search engine to find examples.