Wasted time in timed practice
In timed practice, you have a limited time to answer the questions. The problem is, that the timer still runs after you answer a question but before you continue to the next question. It's disturbing in particular when you usually read the questions discussions with the button "Discuss sentence".
My suggestion is to stop the timer when the user presses the button "Check" (unless the user did mistakes and he should fix them with the button "Fix mistakes"), and to continue it when the user presses the button "Continue".
What do you think?