Basically they belive that the whole education system is totally mean on the working class (proletariat) - obviously though dont say mean!
A good Marxist to use is Engels and he basically says (as do all of them) that the education system mirrors that of working life and opresses the working class in the same ways.
For example the hierarchy of the headteachers and teachers etc is compared to having bosses and people above you who tell you what to do.
Marxists also say that the upper class or middle class benefit more from education and the way the national curriculum is run.
IE it is more suited to middle class children .... apparantly!!
Another thing you could add which is one I used a lot. They believe that the whole education system is pants because things like text books and extra stuff for school are only going to be able be bought by middle or upper class kids which means working class kids wont ever learn
Also add in all that stuff about labelling and how teachers discriminate against lower classes because of the past labels and stereotypes etc. Labelling theory is immense as you can write loads on that - check out the study by Rosenthal and Jacobsen (called pygmalion in the classroom) They werent marxists but its helpful to use as evidence for marxist theories.
And a conclusion could be something like Marxists think its just gona go round and round in a circle as nobody is going to change and we all hate working class in there views!
Obviously reword this though!!!
Oh and by the way I did that from my memory and I did Sociology of education in as about 2 years ago so year may awant to get a few more facts although I think everything i have written is true. Just to add I did actually get an A in this particular exam so you can trust me!
Ok now I really need some sleep my brain is burnt out!!
You better ace the exam now!
Good luck!