FAQs

For answers to other questions, do just ask in any of CS50’s communities!

Assessments

Does CS50x have a test or quiz?

Nope! CS50 at Harvard does have a test and quiz, but CS50x does not.

What’s the difference between “less comfortable” and “more comfortable” problems? Do I have to do both?

In some earlier problem sets, you’ll have a choice between a “less comfortable” and a “more comfortable” problem.

The “less comfortable” are what you might consider the “standard” version of the problem, designed for students who have little or no prior experience. The “more comfortable” are the “challenge” version, designed for students who consider themselves more comfortable due to prior study/experience before this class. As such, they may require more concepts than have been covered in the course so far.

If you find yourself really struggling with the “more comfortable” version, you should switch to the “less” version (or if you’ve already completed that, simply move on and perhaps revisit in a later week). It would be better for you to skip the problem than to become so frustrated as to drop out of the course entirely. For reference, in the Fall 2019 Harvard class, only 20-30% of students submitted the “more comfortable” problems.

You don’t get any extra points for doing the “more comfortable” problems. If you submit both, the one with the highest grade will count towards your overall course progress.

If I submitted a problem and did not reach the 70% passing grade, can I resubmit?

Yes! You may resubmit; we will only count your most recent submission towards your progress.

If I completed a “week” in CS50x 2020, do I now have to complete the “lab” as part of that corresponding week in CS50x 2021.

No. Per a question that appears below, you have been credited with having completed the full “week” (including the lab) in CS50x 2021 if you completed the corresponding week of CS50x 2020.

Certificates

I completed CS50x in 2020 (or prior). Why does my Gradebook no longer show me as having completed the course?

CS50x is a course that spans multiple years, but has a content refresh on 1 January each year. Your gradebook will only ever reflect your completion status of the current version of the course (which is now CS50x 2021), even if you have completed the course in a prior year. If you wish to get the green banner back, you can complete whatever assessments are missing for the current version of the course, but your free CS50 Certificate is still available at certificates.cs50.io, and eligibility for a Verified Certificate is unaffected so long as you saw the green banner atop your gradebook at least once.

Do I have to pay for verification before starting the course?

Nope! If you would like a verified certificate from edX, you can pay for verification at any point, even after completing all of the coursework. Though we do recommend, to avoid any logistical issues that can delay certificate issuance, that you verify before finishing the course.

If I paid for a verified certificate before 2021, do I need to pay again?

No, your verification should be good for an entire year, but if it has expired, you should be able to re-verify yourself via edX’s dashboard.

How do I get my free CS50 Certificate?

Once you have completed the course and met all of the requirements, you’ll see a link on your CS50x Gradebook page allowing you to request a free CS50 Certificate, much like the one shown here. This link will be available within approximately four hours, and you can then log in and obtain your certificate by using your GitHub credentials. If you have trouble accessing it, try logging out of GitHub and back in, then revisit the link to download your certificate. Be sure to request your certificate before 1 January 2022.

How do I get my verified certificate from edX?

Every few weeks, CS50’s staff provides edX with a list of students who have satisfied CS50x’s requirements (by receiving scores of at least 70% on every required problem submitted as part of the course’s ten problem sets, the ten labs, as well as on the final project). Typically within a week thereafter, edX then generates students’ Verified Certificates (for students who have active Verification), at which point they should appear automatically on edX’s dashboard. Note that edX will not notify you, so be sure to check your dashboard periodically.

If it has been more than a month since you met all requirements and you have still not received your certificate despite holding an active Verification that whole time, email certificates@cs50.harvard.edu with your details. Please do not email sooner; we cannot accept requests for expedited processing of Verified Certificates.

How do I know if I have completed all requirements for a certificate?

Your CS50x Gradebook shows the scores for each 2021 problem submission and progress you have made for each week. When you have completed requirements for a given week, the week number will be shown in green, and your progress indicator will be updated to reflect that. Once you have completed all requirements, you will see a green banner atop that page, confirming your completion.

What’s the difference between a verified certificate and a CS50 Certificate?

A verified certificate, which you can purchase from from edX, “can provide proof for an employer, school, or other institution that you have successfully completed an online course. Verified certificates require you to verify your identity using a webcam and a photo identification card, so employers and schools know that you completed the course work.”

A CS50 Certificate is a free certificate from CS50 itself; CS50 does not verify identities.

How should I describe my verified certificate on my resume or elsewhere?

You’re welcome to say that you received a verified certificate from HarvardX.

Deadlines

If I don’t finish the course before 31 December 2021, what will happen?

On 1 January 2022, the course will be updated to a 2022 version. Your progress from 2021 will be carried forward to the 2022 version (see below). After 31 December 2021, you may only submit the 2022 version’s problem sets and will need to satisfy whatever requirements are in place for CS50x 2022. Your carryover progress (as described below) from 2020 will not carry forward into 2022, however.

If I started CS50x before 2021, can I resume?

Yes, any progress you made on past years’ problem sets has been carried forward to your CS50x 2021 gradebook. Note that individual problem scores from past years are not shown, but if the corresponding problem set was completed, you’ll see it marked with a green circle and included in your progress bar at the top. Moving forward, though, you must submit CS50x 2021’s problem sets and labs.

Here is how you should transition from the 2020 course to the 2021 course:

Completed in 2020 Resume your studies with
No Problem Sets Week 0 and Problem Set 0 of CS50x 2021.
Problem Set 0 Week 1, Lab 1 and Problem Set 1 of CS50x 2021.
Problem Sets 0 – 1 Week 2, Lab 2, and Problem Set 2 of CS50x 2021.
Problem Sets 0 – 2 Week 3, Lab 3, and Problem Set 3 of CS50x 2021.
Problem Sets 0 – 3 Week 4, Lab 4, and Problem Set 4 of CS50x 2021.
Problem Sets 0 – 4 Week 5, Lab 5, and Problem Set 5 of CS50x 2021.
Problem Sets 0 – 5 Week 6, Lab 6, and Problem Set 6 of CS50x 2021
Problem Sets 0 – 6 Week 7, Lab 7, and Problem Set 7 of CS50x 2021.
Problem Sets 0 – 7 Week 8, Lab 8, and Problem Set 8 of CS50x 2021.
Problem Sets 0 – 7 and all parts of one Track Week 10 and Lab 10 of CS50x 2021.

When are deadlines?

CS50x does not have individual deadlines for assignments. You are welcome to work on and submit at your own pace.

The overall deadline for the course is end of day, Eastern time, on 31 December 2021 (Fri, Dec 31, 2021, 11:59 PM EST). For your convenience, we will often on this website render this time in your local timezone ().

If all required work is turned in before the above time, and ultimately receives a satisfactory grade (whether before or shortly after that deadline), you will be considered to have completed CS50x.

How will work I completed as part of CS50x 2020 carry forward into CS50x 2021?

Equivalence credit was given for work done in CS50x 2020 as follows. Note that you must have completed1 each row in a box in the left column before 1 January 2021 in order to have received credit for the corresponding problem set(s) and lab(s) in the right column. If you have only completed some of the items in a box in the left column, no equivalence credit will be given for that work. (The carryover is done on a per-problem set basis, not a per-problem basis; your individual problem scores will not carryover and will show as 0%.)

Completed1 in CS50x 2020 Credit equivalent in CS50x 2021
Scratch Problem Set 0
Hello
Mario (Less) OR Mario (More)
Cash OR Credit		 Problem Set 1
Lab 1
Readability
Caesar OR Substitution		 Problem Set 2
Lab 2
Plurality
Runoff OR Tideman		 Problem Set 3
Lab 3
Filter (Less) OR Filter (More)
Recover		 Problem Set 4
Lab 4
Speller Problem Set 5
Lab 5
Hello (Python)
Mario (Less) (Python) OR Mario (More) (Python)
Cash (Python) OR Credit (Python)
Readability (Python)
DNA		 Problem Set 6
Lab 6
Houses
Movies		 Problem Set 7
Lab 7
Fiftygram (Android)
Pokedex (Android)
Notes (Android)		 Problem Set 8
Lab 8
Problem Set 9
Lab 9
Pong
Mario (Games Track)		 Problem Set 8
Lab 8
Problem Set 9
Lab 9
Fiftygram (iOS)
Pokedex (iOS)
Notes (iOS)		 Problem Set 8
Lab 8
Problem Set 9
Lab 9
Homepage
Finance		 Problem Set 8
Lab 8
Problem Set 9
Lab 9
Final Project Final Project

1 By completed, we mean you earned a 70% or better on the problem before 1 January 2021.

Will work I completed for CS50x 2020 (or prior) carry forward into CS50x 2022?

Work completed in CS50x 2020 or prior is not subject to carry-forward for progress. Only work completed in CS50x 2021 will carry forward. This means if you received an equivalence credit that carried forward into CS50x 2021, that credit will no longer be valid as of 1 January 2022, and you may need to redo (or at least resubmit!) some assignments. What this effectively means is that, depending on when in the calendar year you begin you have between 12 and 24 months to complete CS50x without needing to circle back and start resubmitting assignments. We know, particularly for folks who are trying to finish the course right at the end of December that this can prove difficult, but unfortunately we cannot make any exceptions to this rule for any reason.

Will work I completed for CS50x 2021 carry forward into CS50x 2022?

Yes, see below. Equivalence credit will be given for work done in CS50x 2021 as follows. Note that you must have completed1 each row in a box in the left column before 1 January 2022 in order to receive credit for the corresponding “week” in the right column. If you have only completed some of the items in a box in the left column, no equivalence credit will be given for that work. (The carryover is done on a per-week basis, not a per-problem basis; your individual problem scores will not carryover and will show as 0%.)

Completed1 in CS50x 2021 Credit equivalent in CS50x 2022
Scratch Week 0
Mario (Less) OR Mario (More)
Cash OR Credit
Lab 1		 Week 1
Readability
Caesar OR Substitution
Lab 2		 Week 2
Plurality
Runoff OR Tideman
Lab 3		 Week 3
Filter (Less) OR Filter (More)
Recover
Lab 4		 Week 4
Speller
Lab 5		 Week 5
Hello (Python)
Mario (Less) (Python) OR Mario (More) (Python)
Cash (Python) OR Credit (Python)
Readability (Python)
DNA
Lab 6		 Week 6
Fiftyville
Movies
Lab 7		 Week 7
Homepage
Lab 8		 Week 8
Finance
Lab 9		 Week 9
Final Project Final Project

1 By completed, we mean you earned a 70% or better on the problem before 1 January 2022.

Eligibility

Is my child too young to take CS50x?

CS50x is perhaps best suited for ages 13 and up. Some of the software tools that the course uses require a minimum age of 13 to sign up. Therefore, younger students might need a hand from a parent in getting set up.

Grades

If my style score is not as expected, why might that be?

Your style grade will be based on the style50 results for every source code file in your submission. When you run submit50, be sure that your folder includes only those files that are necessary for the problem set. If you have any extra test files in there, those will be counted towards your grade. Remove the extra files from the folder and resubmit to get an updated Style score.

Why does edX think my grade is 0%?

CS50x doesn’t use edX’s built-in gradebook, so all students’ scores appear (in edX’s gradebook) as 0%, always. Not to worry, see cs50.me/cs50x for your actual scores. (Note that if you have carryover credit, as described in a question above, you will not see the individual scores for those weeks.)

Support

Does CS50x have office hours?

Not regularly! Afraid CS50x is too large, but you can still ask questions in any of CS50’s communities!

Does CS50x have sections?

Afraid not! CS50x is too large, but you can still ask questions in any of CS50’s communities!