The pre-final exam is here: prefinal.pdf.
To schedule an optional final exam, select one of the open slots here: Thursday, 2 May or Friday, 3 May. You need to sign up to take a final by 4:59pm on Wednesday, 1 May.
If none of the remaining slots work for you, send me email (before 5pm on Wednesday, 1 May) with your scheduling constraints to find another time.
If you choose to take final, you should come with your written answers to the pre-final questions. At your schedule final, I will ask you to explain your answers, ask follow-up questions, and may ask new questions (not related to questions on pre-final). Performance on final can improve or reduce grade (although it will only be reduced in cases where your performance on both the written and oral final makes it clear that your learning in the class is significantly below the level expected for the grade you were assigned before the final).