Mid-Quarter Diagnostic

See About Assessments for an overview of our plan for assessments.

Motivation

The CS106B diagnostic is intended as a way for us to identify early on in the quarter how comfortable you feel with the course material thus far. Since the course material builds on itself, checking that you have a solid grasp of the early foundational material is critical for making sure that you have the right scaffolding to assimilate other concepts that are learned later in the class.

The primary goal of the diagnostic is to provide feedback to you, but we want you to prepare for it and take it seriously, which is why it's worth 15% of your grade. We hope you'll take the diagnostic as an opportunity to see how much you've learned in the past few weeks, as well as what work you have left to do. After taking the diagnostic and receiving your graded feedback, you will also have the opportunity to reflect on your experience taking the diagnostic and your potential areas of growth that you'd like to focus on for the rest of the quarter.

Logistics

• The Mid-Quarter Diagnostic will be available for students to complete between Friday, July 16 (starting at 12:01am PDT) and Sunday, July 18 (ending at 11:59pm PDT). This time period will be referred to in the rest of this document as the "Diagnostic Administration Period."
• The diagnostic will be distributed and administered using a website called Gradescope. You've all been added to a class called "CS106B8" on the website, so you'll need to log in to Gradescope to view the class. Please not that you'll probably need to make an account through Gradescope, and you must use your Stanford Email in order to be authenticated.
• The diagnostic will be designed to be completed in about an hour to an hour and a half, but students will have the opportunity to work on the diagnostic for up to 3 hours if they so choose. This decision has been made to eliminate any time pressure when it comes to answering the questions on the diagnostic.
  • Students with OAE accommodations will receive extended time to complete the diagnostic pursuant to the specifics of their accommodations. More details will be sent out via email to the students for whom this information is relevant.
• Each student will select a three-hour time period that is entirely contained within the Diagnostic Adminstration Period during which to take the diagnostic. You do not have to communicate with us when you plan to take the diagnostic. However, your diagnostic download and submission times will be monitored, and both download and submission must happen within a three-hour time span.
• The assessment will be open-note, open-book, and open-internet. You are prohibited from seeking help from other human beings ( fellow students, friends, family, folks on the internet, discussion forums). You may consult only inanimate sources of information. You can find more information on the Honor Code and how it applies to the diagnsotic below.

Honor Code

• We expect you to uphold your obligations to the Stanford Honor Code for the assessment, just as with all coursework.
  • You are not to give nor receive unpermitted aid of any form.
  • The work you submit is expected to be your independent, original work; not jointly developed nor derived from the work of another.
  • You are not to discuss the content of the assessment with any other person (except for private, individual communication with the course staff to ask clarification questions). This restriction applies during your assessment and afterwards up until the time period closes for all assessments to be completed.
  • The prohibition against sharing or discussing the assessment applies to the content in any form (verbal description, problem text, solution diagrams or code, and so on) and through any media (private conversation, email, Ed post, internet forum, etc.)
• To help guide your preparation and access of resources during the diagnostic, here is a non-exhaustive list of permissible and impermissible resources that you can access while taking the diagnostic
  • Permissible (Allowed)
    • Looking at any materials posted on the course website (lecture slides, section problems, practice diagnostic problems, etc.)
    • Using Qt Creator or Ed to run code samples
    • Use a Google search to find online materials related to course content
    • Making a private post on Ed to ask a clarifying question about the wording of a problem
  • Impermissible (Not Allowed)
    • Making a public post on Ed about the questions on the diagnostic
    • Talking to another person (besides Susan, Trip, or a section leader) about the questions on the diagnostic
    • Making a post on Stack Overflow (or related online websites) about the content of the diagostic
    • Discussing any information about the diagnostic with someone who is not on course staff any time during the entire diagnostic window

Format

• The general format of the diagnostic will be a collection of questions that involve both reading/understanding provided code and writing code to solve a provided problem.
• When a student is ready to start the diagnostic, they will visit gradescope and click on the assignment called "Mid-Quarter Diagnostic," which will appear at the start of the day. The exam questions, with text boxes for your nswers, will be accessible there.
• Students will then have up to 3 hours (or more, if provided by OAE accommodations) to work through the content of the diagnostic on Gradescope. All answers and code will be typed directly into Gradescope. We do not recommend writing code in Gradescope because the tab key does not work properly. Rather, we will also provide a .txt file for you to type up your answers in. You can copy and paste your answers from the text file into Gradescope.
  • It's worth noting that you may be tempted to run / test your code in Qt creator or another C++ IDE. We do not recommend this. We are less concerned with syntax and more concerned with the correctness of the ideas that your code is conveying. Historically, students who try running their exam code are far liklier to not finish their exams compared to their counterparts.
• Upon completion of the diagnostic, students will submit their answers through Gradescope via a "submit" button. If you have any issues accessing or submitting your diagnostic via Gradescope, please contact Trip or Susan.

Content

The diagnostic will cover up through week four of the course, with the last lecture included being Wednesday, July 14. Material covered will include the first four section handouts, as well as assignments 1 through 3. In particular, we will divide the diagnostic into a few topics, which you should be familiar with:

• ADT's (writing code)
• Big-O (runtime analysis of functions)
• Recursion (tracing output and writing code)
• Recursive Backtracking

Practice Materials

The practice diagnostic questions have been posted. We highly recommend working through the problems in a realistic envrionment first (set aside 1.5 hours of your time to work through it, collect all the resources you plan to use during the actual diagnostic) before choosing to look at the solutions.

In addition to working through the practice diagnostic, we highly recommend starting your studying by working through the lecture examples and section problems posted on the course website. In particular, try working through section problems that you didn't get a chance to touch on during section. These problems provide a great opportunity for you to test your individual problem-solving merit! We add way more problems to the section handouts than can feasibly be covered in a 50-minute section for exactly this reason.

Finally, in the spirit of giving you more practice resources, we are also going to link some practice problems from exams that have been distributed in prior quarters. Please note that the overall composition of these problems should not be used as an indicator of the composition of the diagnostic, nor the complete set of topics that are going to be covered. These files have been made by other instructors for other versions of the class that are similar but not completely the same, and none of them have been developed under the context of digital learning. However, you may find individual problems contained within to be good practice of the material we've covered in the first three weeks of our course.

• Additional practice problems
  • You can replace any instance of HashSet and HashMap with Set and Map, respectively, since we have no yet covered the hashed versions of these data structures in our class. These data structures have the same associated methods that you can use, but their runtimes may be different.
  • Please note that since these problems are taken from across various exams, the numbering will not be consistent. You should use the problem names/descriptions to match them to their solutions, which will appear in an identical order as the questions appear in the practice problem file.
• Additional practice problem solutions

Strategies

Assessments in the CS106 courses can be challenging. You may be unsure of how to make sure the skills you use on assignments will translate well to the timed diagnostic setting. The practice diagnostic gives an idea of what to expect, and this handout gives some sage advice gathered from our current and past staff members. We hope you will find our tips useful! Remember: We are assessing your ability to think logically and use appropriate problem-solving techniques. We expect you to express yourself in reasonably correct C++, but we will be quite lenient with errors that are syntactic rather than conceptual.

Digital diagnostics

Given the transition to online learning, we will be administering the diagnostic digitally. While a digital coding diagnostic might seem similar to working on an assigment, we want you to approach the assessment more similarly to if it were being administered on paper. For example, we have deliberately designed the exam to prevent you from running your code during the diagnostic. In particular, in a time-restricted situation, immediate feedback can sometimes be more of an impediment than an advantage. Imagine this: you read the first problem, have a good idea how to solve it, write your solution, and trace its operation and feel good. You compile and test it. Suppose it exhibits a bug — even though it may only be a minor issue, you can see that your answer is wrong so you hunker down and rework and retest until it's perfect… even if it takes the whole time. Bad deal – since you never got to the other problems! We want you to write your best answer and move on, and if you have time to double-check your work at the end, you can do so then.

How to study for the diagnostic

"Open Resource" doesn't mean "No Review Required"

The diagnostic is open-resource, and you can refer to slides, the textbook, your notes from lecture, course handouts, and your assignments. We don’t expect you to memorize minute details, and the diagnostic will not focus on them. However, this doesn’t mean you shouldn’t prepare. There certainly isn’t enough time during the diagnostic to learn the material. To do well, you must be experienced at working through problems without needing to repeatedly refer to your resources.

Practice, practice, practice

A good way to study for the programming problems is to take a problem (from lecture or section or a sample diagnostic problem) and write out your solution under test-like conditions. This is much more valuable than a passive review of the problem and its solution, when it becomes too easy to conclude “ah yes, I would have done that,” only to find yourself adrift during the real diagnostic when there is no provided solution to guide you!

Get your questions answered

If there is a concept you’re a bit fuzzy on or you’d like to check your answer to a chapter exercise, or you wonder why a solution is written a particular way, get those questions answered before the diagnostic. Swing by the LaIR, come to office hours, or post on Ed, and we’re happy to help.

How to take the diagnostic

Scan all the problems first

Quickly peruse all questions before starting on any one. This allows you to “multitask”—as you are writing the more mundane parts of one answer, your mind can be brainstorming strategies or ideas for another problem in the background. You can also sketch out how to allocate your time between questions in the first pass.

Spend your time wisely.

There are only a handful of questions, and each is worth a significant amount. Don’t get stuck on any particular problem. There is much opportunity for partial credit, so it’s better to make good efforts on all problems than to perfect one answer while leaving others untouched.

Style and decomposition are secondary to correctness.

Unlike the assignments where we hold you to high standards in all areas, for a diagnostic, the correctness of the answers dominates the grading. Decomposition and style are thus somewhat de-emphasized. However, good design may make it easier for you to get the functionality correct and may require less code, which takes less time and provides fewer opportunities for error. Comments are never required unless specifically indicated by a problem. When a solution is incorrect, commenting may help us determine what you were trying to do when we attempt to give partial credit.

Pay attention to specific instructions

A problem statement may include detailed constraints and hints. These constraints are not intended to make things difficult; typically, we are trying to guide you in the direction of a more straightforward solution. If you disregard these instructions, you are likely to lose points, either for not meeting the problem specification and/or for errors introduced when attempting a convoluted alternative.

Syntax is not that important if it is clear what you mean.

We won’t trouble you about most small syntax errors (forgetting semicolons or spaces, for example) as long as your intentions are clear. Having said that, beware that if your syntax errors cause ambiguity, we might not get the correct meaning. For example, if we see a for loop followed by two lines with no curly braces, where both lines are vaguely indented or a third line has been added in after the fact, we may be confused about what code is really inside your for loop.

Save a little time for checking your work.

Before submitting your diagnostic, reserve a few minutes to go back over your work. Check for matching parameter names passed into functions, etc. We try not to deduct points for minor things if it is obvious what you meant, but sometimes it is difficult to decipher your true intention. You might save yourself a few lost points by tidying up the details at the end.

Miscellaneous Helpful Resources

• Syntax Reference Sheet
• Advice from Keith Schwarz about coding without an IDE
• Advice from Julie Zelenski about coding assessments

Final Thoughts (Advice and Encouragement)

Always remember why you are at school. Learning and education tend to be a more fulfilling goal than high grades. If you work hard, study lots and feel good about your understanding of computer science that is an achievement to be proud of—regardless of how many points you get relative to the other students in the class.