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SQL Easy is a free interactive SQL tutorial offering 31 exercises that run against a real SQLite database in the browser. It provides hints when users are stuck and immediate feedback when a query is correct, and requires no signup. It is built by the team behind Beekeeper Studio.
SQL Noir provides educational videos, lessons, tutorials, or self-learning resources.
SQL PD provides educational videos, lessons, tutorials, or self-learning resources.
SQL Practice provides educational videos, lessons, tutorials, or self-learning resources.
SSC provides educational videos, lessons, tutorials, or self-learning resources.
Stack Exchange operates a network of over 180 community-powered question-and-answer websites covering a wide range of specialized topics. Users can ask and answer questions on niche subjects across the network's sites, which include communities for mathematics, physics, law, programming, and other fields.
StarlingDB provides educational videos, lessons, tutorials, or self-learning resources.
An interactive book for learning SQL that runs queries against a real-world dataset. It states it is free of charge, free of ads and requires no registration or downloads. Chapters are designed to take about 30 minutes each.
Stat Trek provides free online tutorials and calculators covering statistics and probability. Tutorial topics include AP Statistics, probability, linear regression, ANOVA, survey sampling, and matrix algebra, explained in plain English. The site also offers practice exams and a random number generator and sample size calculator for statistical work.
Staying is a code visualization platform for Python, JavaScript and C++. It animates execution flow, traces variables and monitors memory allocation, and offers code optimization suggestions. The documentation collects language support, data-structure examples and runnable code.
Stellarium is a free open source planetarium for computers. It shows a realistic sky in 3D, as seen with the naked eye, binoculars or a telescope, and offers time control, telescope control and a plugin system. The site describes it as easy to use and provides a features list and system requirements.
Stimuler IELTS Speaking Buddy provides educational videos, lessons, tutorials, or self-learning resources.
Stitz Zeager Open Source Mathematics provides free and open precalculus materials, including College Algebra, College Trigonometry and Precalculus textbooks by Carl Stitz and Jeff Zeager. A Precalculus 4i edition is available free on the interactive Ximera platform. Printed desk copies are offered to Verified Teachers through openintro.org.
Storied Colors is a catalogue of historical named colors with documented sources, including provenance and chemistry. Entries are published weekly, and the site states that AI assists drafting while entries are checked before publication. It is maintained by one person.
A collection of guides on building and customizing startpages. Topics include reverse image searching, setting the new tab page in Chrome and Firefox, creating search bars with DuckDuckGo, and building terminal-like and basic startpages. The guides are not categorized, and the author states none are made for a specifically technical audience.
StringScales is a free browser-based tool for visualizing scales on stringed instruments such as guitar, bass, banjo and ukulele. Users can pick a scale, build chord progressions and tag each chord with a scale, then play along with a backing band while the fretboard highlights the notes. No account is needed, and a free account adds saving of progressions.
Strml provides educational videos, lessons, tutorials, or self-learning resources.
Stroke Order provides educational videos, lessons, tutorials, or self-learning resources.
Strong ASL is a site for learning American Sign Language, offering over 2,000 signs with video examples and tutorials and the ASL alphabet. It includes a searchable sign database, alphabet and fingerspelling lessons, quizzes, and an AI feature that interprets user signs and gives feedback.
Studocu provides educational videos, lessons, tutorials, or self-learning resources.
Study Hatch is an educational site for IGCSE and A Levels with past papers and classified questions from CIE, AQA and Edexcel. It offers content search, an IGCSE score calculator, a custom exam PDF builder and an AI assistant. Premium VIP plans are available.
StudyCraft is an open source, free study tool available for Windows, MacOS and Linux. It allows users to import study materials including PDFs, Markdown files, webpages and GitHub repositories, which are automatically indexed into a vector database for semantic search. Users can customize their imported content, and the tool automatically generates flashcard decks and practice tests, plus provides study session analytics to track progress. It supports self-hosted and cloud-hosted large language model integrations and is built for fast performance.
StudyKit provides educational videos, lessons, tutorials, or self-learning resources.
StudyKit is a free student resource toolkit that provides over 50 tools across maths, science, writing and study categories. The toolkit includes calculators, timers, mind maps, flashcards, quiz generators, exam countdown trackers, and writing assistance tools for student use.
