CS50

Live from Harvard University at 1:30pm EDT, this is Week 6 of CS50 on Python. Open to anyone online. To attend in person some day, see cs50.ly/attend. This lecture will become part of CS50x 2026 on edX on January 1, 2026.

On Zoom at cs50.zoom.us/meeting/register/3ww17N-5Tdm46Hq4hm7s….

On YouTube at youtube.com/live/KV2Nib7w3Kg.

1 week ago (edited) | [YT] | 424

CS50

🧩 The first-ever CS50x Puzzle Day in London is this Friday, October 10, 2025 at 5:00 PM British Summer Time, hosted at Meta by Professor David J. Malan, Professor Daniel Wilson from Oxford Lifelong Learning, University of Oxford, Professor Tom Crawford from Oxford (and University of Cambridge and Tom Rocks Maths), and CS50's alumni and friends at Meta.

See www.eventbrite.com/e/cs50x-puzzle-day-at-meta-in-l… for all details, including tickets. (Please forgive that space is limited!) Tickets available until 4pm on October 8, 2025. If ticket price would prevent you from attending, email outreach@cs50.harvard.edu.

If unfamiliar, CS50x Puzzle Day is an opportunity to collaborate on teams of 2, 3, and 4 to solve a packet of puzzles (i.e., logic problems). (Your team members don't need to have taken CS50x itself.) Among the event's goals is to send a message that computer science is more about problem-solving than it is about, say, programming. Puzzles are not programming challenges. No prior CS or programming experience needed, just logic and smarts! No team? No problem! We will help teams form at the event.

1 week ago | [YT] | 424

CS50

Live from Harvard University at 1:30pm EDT, this is Week 5 of CS50 on data structures and more. Open to anyone online. This lecture will become part of CS50x 2026 on edX on January 1, 2026.

On YouTube at youtube.com/live/Sca41aXoj5U.
On Zoom at cs50.zoom.us/meeting/register/7ArT05-PSkGfYvc4fYr5….

To attend in person some day, see cs50.ly/attend.

1 week ago | [YT] | 896

CS50

Live from Harvard University, this is Week 4 of CS50 (on memory and more). Open to anyone online. This lecture will become part of CS50x 2026 on edX on January 1, 2026.

On Zoom at cs50.zoom.us/meeting/register/QB1SwwygTwmEw3zdrcsf….
On YouTube at youtube.com/live/aQFbviJheVE.

To attend in person some day, see cs50.ly/attend.

2 weeks ago | [YT] | 1,324

CS50

Live from Harvard University at 1:30pm EDT, this is Week 3 of CS50 on algorithms. Open to anyone online. (Or attend in person some day, per cs50.ly/attend.)

Watch on YouTube at youtube.com/live/4eN3_kbbhSY.

Register for Zoom at cs50.zoom.us/meeting/register/aHHyesHWSui558Kzq-1F….

3 weeks ago | [YT] | 211

CS50

Hello, world! CS50 will again be offered at Oxford Lifelong Learning, University of Oxford in Michaelmas and Hilary terms. To attend online, register at lifelong-learning.ox.ac.uk/courses/introduction-to…

Taught over 12 weeks, this course teaches you how to solve problems, both with and without code, with an emphasis on correctness, design, and style. Topics include computational thinking, abstraction, algorithms, data structures, and computer science more generally.

4 weeks ago | [YT] | 1,013

CS50

Live from Harvard University at 1:30pm EDT, this is Week 2 of CS50 on arrays and more. Open to anyone online. (Or attend in person some day, per cs50.ly/attend.) 

On YouTube at youtube.com/live/2Z-UFxZAl9M.
On Zoom at cs50.zoom.us/meeting/register/Appx-dHlTse_yJf_y-PM….

1 month ago | [YT] | 880

CS50

Live from Harvard University at 1:30pm EDT, this is Week 1 of CS50 on C. Open to anyone online. This lecture will become part of CS50x 2026 on edX on January 1, 2026.

On YouTube at youtube.com/live/2Lg0W1_JMs4.

On Zoom at cs50.zoom.us/meeting/register/YAxc6OdRRLua_KKCAb8l….

Or, to attend in person some day, see cs50.ly/attend.

1 month ago | [YT] | 1,633

CS50

Live from Harvard University on Wednesday, September 3, at 1:30 PM EDT, this is CS50's first lecture of Fall 2025, aka Week 0, on:

Computer Science. Computational Thinking. Problem Solving: Inputs, Outputs. Representation: Unary, Binary, Decimal, ASCII, Unicode, RGB. Abstraction. Algorithms. Running Times. Pseudocode. Scratch: Functions, Arguments, Return Values; Variables; Boolean Expressions, Conditionals; Loops; Events; Threads.

Open to anyone online. Or register to attend in person at cs50.ly/attend. This lecture will become part of CS50x 2026 on edX in January 2026.

Convert to own time zone at time.cs50.io/20250903T133000-0400/20250903T161500-….

On Zoom at cs50.zoom.us/meeting/register/_wovJOJ2R0aIUDHQFNH2….

On YouTube at youtube.com/live/6px2ii_x52A.

1 month ago | [YT] | 1,275

CS50

Hello, world! ‪@cs50‬'s lectures in Sanders Theatre at ‪@harvard‬ University are open to the public, September 2025 – November 2025. Whether you are (or were!) a student or teacher of any of CS50's courses, or just CS50-curious, you are welcome to attend CS50's lectures in person in Cambridge, Massachusetts, USA. Fall 2025's lectures will become part of CS50x 2026 on ‪@edXOnline‬.

To attend in person, visit cs50.ly/attend.

To watch online instead, register at cs50.ly/watch.

SCHEDULE

• Scratch on Wednesday, September 3, 2025 at 1:30 PM – 4:15 PM EDT
• C on Monday, September 8, 2025 at 1:30 PM – 4:15 PM EDT
• Arrays on Monday, September 15, 2025 at 1:30 PM – 4:15 PM EDT
• Algorithms on Monday, September 22, 2025 at 1:30 PM – 4:15 PM EDT
• Memory on Monday, September 29, 2025 at 1:30 PM – 4:15 PM EDT
• Data Structures on Monday, October 6, 2025 at 1:30 PM – 4:15 PM EDT
• Python on Wednesday, October 8, 2025 at 1:30 PM – 4:15 PM EDT
• SQL on Monday, October 20, 2025 at 1:30 PM – 4:15 PM EDT
• Artificial Intelligence on Friday, October 24, 2025, at 12:00 PM – 1:00 PM EDT
• HTML, CSS, and JavaScript on Monday, November 3, 2025 at 1:30 PM – 4:15 PM EST
• Flask on Monday, November 10, 2025 at 1:30 PM – 4:15 PM EST
• The End on Monday, November 17, 2025 at 1:30 PM – 4:15 PM EST

1 month ago | [YT] | 1,306