in regards to history (or english) the BOS has a glossary of key words. The main ones you will need to know are
(note this is a summary not exactly what is on the BOS list)
analyse - divide issue into different parts and describe each of them and then evaluate the issue
assess - make a judgement of value, quality and outcomes
compare - show how things are similar / different
critically - add a degree or level of accuracy, depth, knowledge and understanding, logic and questioning to answer
discuss - identify issues and provide poitns for and / or against
evaluate - discuss and come to an informed conclusion about how effective or ineffective something is
explain - relate cause adn effect, make the relationship b/w things evident
so with your question on Trotksy if you had to assess his role in teh consolidation of power and events leading to his excile you would need to make a judgement about how important his actions actually where compare to other factors (ie. for the consolidation of bol. power - how important was Trotksy compared to Lenin? or with his excile how important was trotksy actions compared to the actions of Stalin? - then in your conclusion you woudl put forward somethign that you think was the most likely)
evaluate is very similar to assess - and i have always found that basically you are doing the same thing but you tend to way up both sides of the argument a little bit more.
