"Thoroughly think about the conceptual data model of your web application: Which are the basic entities your web application has to deal with, and how they are related to each other? For this purpose, use a UML class diagram (https://en.wikipedia.org/wiki/Class_diagram) to design such a conceptual data model."
Form - definitions of feedback forms (e.g. 'Feedback form for Java developers')
Matrix - definitions of competency matrixes (e.g. 'Matix of Competencies for Java devs')
MatrixCharactiristic - definitions of matrixes' competencies (e.g. 'Java Core', 'Leadership')
Feedback - a feedback left by emploee X on emploee Y
Competency - a grade given by employee X that evaluates emploee Y's competency in specific MatrixCharactiristic (e.g. 'Java Core' 5 out of 10, 'Leadership' - 9/10).
PS: 'out of X' is a max value of the hardcoded scale
"Thoroughly think about the conceptual data model of your web application: Which are the basic entities your web application has to deal with, and how they are related to each other? For this purpose, use a UML class diagram (https://en.wikipedia.org/wiki/Class_diagram) to design such a conceptual data model."