Thank you very much for the advice you have given me.
How do you make a duplicate of such a template?
Is it OK if I go to Edit Mode and copy the content and paste it in another page eg: my sandbox? This is what I do now, when I want to study the code of any interesting page or a template.
I looked at the templates you are designing; AnswerBox. Probably you will be able to modify these tables to include "Feedback" property in the cells of the second column. Then we can use that template as an iDevice for "Self Assessment"
Yes, I just cut and paste the content into another page. If it is template content then I usually cut and paste it into a new template (something like Template:<myTestTemplateName>). I usually forget but it is a good idea to put a comment in the summary text field to say where it came from. As you mentioned, other content is easily to cut and paste into your sandbox.
Good idea for the AnswerBox template. There is a Template:Self Assessment that has a slightly different method for providing feedback.