Before a volunteer research assistant runs subjects in a study, they must be trained in the ethical requirements for using human participants in research. The Collaborative Institutional Training Initiative (CITI) has a website on which they provide such training.
It consists of various web based courses, but research assistants only need to take the one entitled "Social & Behavioral Research - Basic/Refresher - Basic Course" (you do not need to take "Social and Behavioral Responsible Conduct of Research"). There are 13 modules, each followed by a short quiz. The lessons may seem at first to be very in depth. However, the material in each lesson provides the information you need to do well on the quiz. There will also be links to more detailed material that you can look at for a deeper understanding, but you can just briefly scan such additional material to see what it's about.
If you do all of the lessons at one time, it would take perhaps 4 or 5 hours to do the whole course. It is better to do a couple of lessons at a time. Once you have registered, you can log back in using the username and password you provide and pick up where you left off.
When you finish the last lesson, your certificate will be presented on the screen so that you can print it. If you don't print it at that time, you can log in later and do so. However, it is best to be on a computer from which you can print when you do the last lesson so that you can just go ahead and print your certificate.
To take the course, download the instructions from the link below and follow them.
Detailed instructions with screen shots of the various screens on the web page can be downloaded as a .pdf here: Instructions for CITI ethics certification.