For about a third of the homework assignments, groups will present their solutions orally to Jeff or one of the TAs instead of submitting a written solution set.Which Homeworks?
After HW0 was submitted, we randomly partitioned the students into three clusters:You can look up your assigned cluster on Compass Gradebook after HW1 is released. We will ask you to tell us your group membership in advance; we will assign everyone in the same group to the same cluster. You are free to change homework groups at any time, without notifying us, but you must present the homeworks assigned to your cluster.
- The first cluster will present HW1, HW4, and HW7.
- The second cluster will present HW2, HW5, and HW8.
- The third cluster will present HW3, HW6, and HW9.
Pairs of students can swap clusters at any time during the semester, provided the swap allows both students to present the same number of homeworks. (For example, you cannot swap into cluster 1 during the week that HW2 is due.) To swap clusters, send email to one of the TAs with both students' names and NetIDs. If you are interested in switching clusters but don't know anyone in your desired cluster, we recommend posting to the course newsgroup.
For all homeworks after HW0, groups of up to three people can submit/present a joint solution. You can form a group with anyone you like, as long as you present the homeworks in your assigned cluster.
When and Where?
Presentation sessions will take place each Tuesday and Wednesday afternoon from 1:30 to 4:00, simultaneously in 1212 Siebel and 3304 Siebel. Please contact Jeff as soon as possible if your class schedule conflicts with all of these times.
Sign-up sheets will be posted outside 3304 Siebel Center (the “Theory Lab”) several days before each homework deadline. Each homework group must sign up for a 30-minute time slot no later than Monday evening. There are 20 time slots per week, which should be more than enough to accommodate everyone. Wednesday slots are considerably more popular; if you cannot present on Tuesday, be sure to sign up early!
Each group member that actually shows up gets the same grade for each homework problem. If you miss the time slot your group signed up for, you get a zero for that homework. If you absolutely must reschedule your presentation because of an unexpected emergency, contact one of the TAs at least 24 hours in advance.
How?
Each presentation session lasts 30 minutes, split roughly into three 10-minute chunks, one for each homework problem. Each student in the group is asked to present one problem. The TA determines which student presents which problem by rolling dice, drawing straws, or some other random process.
Each student presents as much of their solution as possible without help from their teammates; the TA determines an individual score based on the student's presentation. Then if necessary, the other group members may chime in to help; the TA then determines another group score based on the entire group's presentation. Every member of the group receives the average of the individual and group scores for each problem.
On average, each problem should take 10 minutes to present; some will take more, others less. However, the entire presentation must be finished in 30 minutes.
For groups with three members, each student presents one problem, with help from the other members if necessary. If a group has only two members, each student presents one problem, with help from their partner if necessary; both students present the third problem together. If a group has only one member, that student presents all three problems without help.
It's all a lot simpler than it sounds!
Advice on Presenting Homeworks
Oral homework scores are based not only on the completeness and correctness of the solution, but also on the clarity of presentation. Here are some suggestions for giving good homework presentations.
- Write down a complete, detailed solution, even though you won't actually submit it. Often writing your solution in full detail is the only way to expose subtle errors; writing will also help clarify the important points in your own mind. You may also want to refer to your written solution when you present.
- Present clearly. Know exactly what you're going to say before you start. Start at the beginning, move step by step until the end, and then stop. Use complete English sentences with correct grammar. Start writing at the top of an empty whiteboard and move downward, just like you're writing on a piece of paper. Don't touch the eraser until your presentation is over. Religiously avoid the words "this" or "it"; give things names and use them consistently. Define your terms. Explain your notation. Don't assume the TA is a mind-reader or a compiler. Talk to the TA, not to the whiteboard. Speak up.
- Practice. Your first presentation will suck. Don't take it personally; everyone's first presentation of everything sucks. So don't give your first presentation to the TA! Practice. Revise. Practice. Practice again. Revise again. Sleep. Eat. Practice again. And don't just practice in your head; stand at a whiteboard with your other group members and present to them exactly as you plan to present to the TA.
- Give a breadth-first, top-down presentation. Highlight the three or four main points in the first 60 seconds. (For example: "We use dynamic programming. Here's the function we compute. Here's the recurrence. The running time is O(n³).") Then explain each main point in one or two minutes, by breaking it down into three or four smaller points. Then, if you still have any time left, explain the single most interesting and/or non-trivial smaller point in more detail. Assume that the TA is familiar with the course material; don't regurgitate!
- Aim to present each solution completely in 5 minutes. This will be a very ambitious goal, especially during the first weeks. The TAs will stop you after 10 minutes on each problem, so you should practice giving your solution quickly and accurately!
- Don't forget the proof of correctness and runtime analysis. Again, highlight the main points of these arguments, not the low-level details. Your job is to convince the TA that you understand the proof, not to explain every single step.
- If the TA interrupts you, listen! The TA may interrupt your presentation at any time to ask questions, provide or ask for clarification, point out flaws or counterexamples, ask you to skip over details, or something similar. An interruption by the TA often indicates either that you haven't made something clear, or that your solution is actually incorrect, or that the TA is satisfied with the part of the solution you're presenting and would like to hear about something else. Don't panic—we're not out to get you! Just answer the TA's questions to the best of your ability. Even if your solution is wrong, you may still get partial credit, and you might even be able to fix your solution on the fly. Part of the value of the oral presentations is learning to think on your feet while communicating your solutions.
- The "I don't know" policy also works for oral homeworks. If you really have no idea how to solve a problem, just say "I don't know" and nothing else. Don't try to fake it. If your solution is completely wrong, you will get a score of 0.