Build intuition for light-speed invariance, time, and energy before the formulas arrive
3 sections · 7 lessons
Trace why light’s fixed speed breaks everyday velocity addition, then examine how simultaneity depends on the observer's frame.
2 lessonsBuild the moving-clock picture of time dilation, then connect it to length contraction along the direction of motion.
2 lessonsResolve the twin paradox with changing frames and proper time, then connect mass-energy convertibility to the energy wall that prevents massive objects from reaching c.
3 lessonsLight’s speed does not change just because the observer is moving, and that puzzle forces a new way to think about time, distance, and energy. This course gives beginners a physical feel for the core ideas of special relativity, from simultaneity and moving clocks to length contraction, the twin paradox, mass-energy equivalence, and the hard limit set by the speed of light. By the end, you can reason through the main relativistic effects without relying on formal derivations first.
The course covers light-speed invariance, observer-dependent simultaneity, time dilation, and length contraction. It also explains the twin paradox, mass-energy equivalence, and why massive objects cannot reach or exceed light speed.
From project managers and operators to founders, analysts, and teams adopting AI, Fenzo is for people who want to get better at the work they already do.
Anything from using AI for project planning and analysis to improving workflows, decision-making, communication, and delivery. If you can describe the skill or task, Fenzo can build a course around it.
Yes. Tell Fenzo what you do, what you’re trying to accomplish, and where you’re stuck, and Fenzo will shape the course around your role, your goals, and the work you actually have to do.
No. Fenzo adapts to your starting point, so you can begin with the fundamentals or jump straight into more advanced work.
Yes. Fenzo for Business puts the whole team on one plan — shared seats, courses you can assign, and reporting on who has finished what.
See Fenzo for BusinessYou start by describing your goal or taking a short skill benchmark. Fenzo uses that context to identify gaps and shape the learning experience around them.
Yes, Fenzo works in your mobile browser.
Something to operate in every section.
Three findings from decades of learning research shaped how every Fenzo lesson is built.
Average pass rate · Freeman et al., PNAS 2014
What the science says
Students in lecture-only classes are 1.5× more likely to fail.
How Fenzo does it
Every Fenzo lesson is interactive. No passive reading or watching, ever.
You work through itAI does it for you
Skill retention over time · with vs. without practice
What the science says
Offloading thinking to AI erodes the very skills you’re trying to build.
How Fenzo does it
Fenzo makes you do the thinking — guided, but never done for you.
Retrieval practiceRe-reading
Long-term recall · retrieval vs. re-reading
What the science says
Recalling information beats re-reading it for building durable understanding.
How Fenzo does it
Lessons weave in quizzes and recall prompts, so it sticks.