This BBC article sets out in detail how many have resigned from the May government in comparison to other Prime Ministers. 

Just when you thought things couldn't get any more complicated - John Bercow, the Speaker of the House of Commons, has announced that the Executive cannot put forward another vote to Parliament unless the motion put to it had changed substantially in nature. He was concerned that the Government are keeping coming back to Parliament with essentially rehashed versions of the same deal - almost grinding down Parliament until they give in.  Quoting conventions and precedent dating back to the 17th Century Bercow used his power as 'Chair' Speaker to defend Parliamentary rights and effectively scupper Theresa May's attempts at pushing her deal through by attrition.  

Brexit continues to ravage through British politics in the run up to the supposed Brexit date and one of the biggest recent stories is the emergence of the new 'independent group of MP's. These MP's are entirely disillusioned by their parties stances - mostly on Brexit. Most of them are Labour MP's who are fed up with Jeremy Corbyn's leadership. Some are deeply opposed to his alleged reluctance to deal with anti Semitism in the party. In political terms it means that it is another clear sign that the traditional party allegiances and broad church parties are being deeply divided by Brexit in a way no other issue has ever divided them. This perhaps mirrors the country as a whole

It is quite a seismic shift in UK Politics which tends to be very party controlled - this small (and growing group) have also become the 4th largest 'party' in the UK. In a Parliament in which government teeters on a knife edge of support that is quite significant. 

HOW DOES THIS RELATE TO A LEVEL POLITICS STUDENTS?
This is a very good example of party discipline being undermined ; The powers of MP's / backbenchers; The change of party control in the Commons ; The limitations to the power of the whip. 

In another sign of the deep divisions ripping through British Politics at the moment, Environment Minister George Eustice has resigned from the Government due to the proposed delay to Brexit, suggested by Theresa May this week. Eustice is a well known Brexiteer and believes that the Prime Minister, by taking a no deal off the table, has removed any form of bargaining chip for Britain in what he believes should be the final run up to Brexit. 

HOW CAN WE USE THIS IN A LEVEL POLITICS?
His resignation is a good example to Politics students of Cabinet splits and Collective Responsibility - as he felt he could not support the Government policy and therefore had to resign.