Read and play
Start with the first online game in the catalogue, then explore six selected articles.
Play now
Explore the online games in catalogue order, then browse the others.
Random variables, eight distributions, sampling, standard error and confidence intervals: theory and simulations in one coherent path.
ReadA sample, a histogram, several possible models and an interval for the mean: learn what the data can tell us, and what they cannot.
ReadFrom Fibonacci’s puzzle to a formula for every child: proof of the general case, four checked examples, and the roles of a and d.
ReadFrom the box principle to remainders, geometry and subsequences: 25 problems with solutions to reveal after trying.
ReadA chain of formulas born from one idea: pair the extremes, then transform the sum of natural numbers into sums of evens and odds.
ReadDice, coins, an urn, Monty Hall and Poisson: fifteen simulations with observed histograms and theoretical probabilities.
ReadYour logic lab
Computer science quizzes, mathematics games, and clear explanations. Learn at your own pace by following your curiosity.
Short sessions · instant feedback
Which data structure would you use?
Two worlds, one method
From the web to algorithms, one question at a time.
Numbers, shapes, and strategies to put to the test right away.
Test yourself
Short activities, clear goals, and useful explanations after every answer.
Each attempt draws 15 questions from a bank of 100 original questions about hardware, software, operating systems, files, networks, and security. This is an independent, unofficial practice activity inspired by Computer Essentials topics.
StartEach attempt draws 15 questions from a bank of 100 original questions about Web browsing, online search, communication, email, and calendars. This is an independent, unofficial practice activity inspired by Online Essentials topics.
StartObserve the pattern, form a hypothesis and find the next number.
StartDaily challenge • No account required
Use each number only once and combine the four basic arithmetic operations.
Every concept starts with an example.
Understand why, not just the answer.
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