A nice example of committees in action here – Sen. Grassley (R-Iowa), chairman of the Senate Judiciary Committee (who you should have studied as part of the SC appointment process), has taken action to try and get to the bottom of the Hillary Clinton emails scandal. He has issued a letter to a former Clinton aide to identify which emails would be turned over to the government and which would not. To enforce this, he has blocked the Obama appointment of Thomas Shannon Jr., to be undersecretary of state for political affairs.
This is a really good example of the powers of committee chairmen showing what they can do in order to further their powers of investigation. It is also a good example of committees at work, investigating the executive branch therefore showing checks and balances in action. With Republican control of the Senate, it could also be used to show the importance of parties in Congress.
The whole article is worth a read as it identifies the tension between the executive and legislative branches which could be used to show the problems of divided government as well as to inform an essay on the federal bureaucracy.