From the IRB Laws of Rugby Union Website
“Welcome to the IRB Laws of Rugby Union web site. On this site, you can read the Laws, watch video examples and animations to build your understanding of how the Laws are applied on the field of play, and take a self-test exam to check your knowledge.
Registered users can access the IRB Laws exam. The exam covers the 22 Laws, variations for U-19, Sevens and Tens, Referee Signals and the Law Amendment Trials.
After completing the IRB Laws Exam, you can download your personalised awareness certificate. Registration is free and takes only a few minutes.”