Even though the heavy hitters have responded to this I am going to take a swing at a native solution.
I would have a 4 table solution
Table 1 - Training
Table 2 - Groups
Table 3 - Employees
Table 4 - Test Scores
The Trainer can create the training, then create groups and select the employees in the groups and keep the scores. The scores table could be designed to keep not just the score of each employee test but what group and training session.
This structure would allow the evaluations of employees, groups, and trainers from the scoring I am , however, assuming that when you want to get such detail the goal is not to only evaluate the employees but the trainings as well. How else could you know when group size is having a direct affect on scores?
You will need some automation and a few buttons based on the details of the hows of your training structure.
As always Dan is right anything can be done in scripting. If you want me to explain more about my response feel free to contact me.