BBC bitesize - Read all the pages and test yourself with the quiz at the end. 

Craig and Dave - Watch videos 81 through to 84 to cover entire 2.4 subtopic

101Computing - Full of nice tasks that help with revision

Exam question walkthrough - For the questions on 2.4, do questions 10 up to (and including) q13

Logic Gate Game - A fun way to practice logic gates

End of topic test - A test that covers all of 2.4