For students interested in studying computer science, CS 124: Intro to Computer Science I is a starting point. Geoffrey Challen, teaching associate professor in Engineering, recently released the website “learncs.online,” where anyone can learn the course material for free.

“It’s essentially a big chunk of our CS 124 materials,” Challen said. “It’s a publicly-available website that allows students to learn and practice basic programming and computer science.”

This website, released in June, shares much of its infrastructure with the website Challen made for CS 124. Challen is still updating the website, and there are currently 61 different lessons for anyone to try.

Each lesson contains multiple interactive components. Challen explained what students can expect to find in any given lesson.

“We tried to make this as interactive as possible, so every lesson contains a mixture of components that try to explain a particular concept,” Challen said. “We have a lot of playgrounds which consist of code that students can edit and run to let them experiment with things.”

Each lesson also includes interactive explanations from multiple instructors and a coding exercise at the end to help students see if they understood the material.

Challen also said having several instructors providing explanations gives people more options in how they learn.

“For a student going through these materials, they might start with one explanation, and maybe it doesn’t make sense to them, but they’ll usually have several other options that they can watch in order to solidify their understanding,” Challen said.

Challen said the lessons are structured in a way that aims to promote effective learning of the course  material.

“Learning a skill — whether it’s cooking, running or a sport — the foundation for it is consistent, regular practice,” Challen said. “Lasting gains and understanding are based on a lot of small interactions with the same material.”

Challen said that through the various components of each lesson, he hopes people will experiment and make use of the interactive opportunities.

While Challen said he has not been doing much to promote the website, the site currently has roughly 1,200 created accounts and 80,000 submitted homework problems.

Colleen Lewis, associate professor in Engineering, contributed many explanations to the lessons about Java — one of the coding languages taught in the course. Lewis said she hopes the website will provide a healthy mindset about computer science.

“I hope that it gives people the right mindset about learning computer science,” Lewis said. “It’s not  about just already knowing it, it’s about having the support to engage in really helpful practice. Like learning a musical instrument, it’s helpful to have a tutor or teacher who can help you practice effectively.”

Challen said he hopes this website will improve the accessibility of computer science as a field.

“In computer science, one of the things we’ve struggled with for a long time is trying to make our field more accessible and welcoming,” Challen said. “I think there’s something nice about a student being able to hear multiple perspectives and multiple different voices.”

Lewis said anyone can start with the website as their first experience in computer science.

“You can just dive in without any experience, but it might be helpful to have people who will encourage you when you get frustrated,” Lewis said. “Because it can get frustrating, but that doesn’t mean you won’t be successful in learning it.”

Lewis said that while this website is helpful for people interested in pursuing a career in computer science, she believes that knowing the basics can benefit anyone.

“I think this tool is really helpful for people who are really interested in a career in computer science, but I think it’s not only helpful for folks like that,” Lewis said. “By getting some experience in programming, it can make some of the computational world that’s all around us seem a little less mysterious.”

Challen said he feels he has a duty to publicly share this website.

“I think this goes along with the University’s public mission,” Challen said. “We have some degree of public responsibility to not only educate students who are paying to come here, but also to contribute to the general dissemination of knowledge.”

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