Problems, labs and notes

A problem has a statement, sometimes a short theory primer, and a worked solution. Problems are tagged by level, difficulty and type (Conceptual, Numerical or Python-coded). Anyone signed in can add one.

1. Try it first

   The solution starts closed. Work it out, then press Show solution to check. When you are stuck partway, One step at a time opens just the first step: read it, try again, and press Next step only when you need more.

2. Mark it

   I Understood This is your own tracker. A written problem has no single answer to check, so it is an honest note for your dashboard, not a score.

A quiz is one question. Answer it and see at once if you are right, with the explanation. Answer it right and it counts as mastered on your dashboard. Keep any quiz in a question vault.

A lab is a starter script and real Python that runs in your browser. Press Run and your code runs on your own device: no installing, no account needed to try it. You can give input values for scripts that ask for input(), and save a run to look at later.

Many labs check your answer for you. After a run, a list shows each check with a tick or a cross, and a hint under each one still to fix. When your code stops with an error, a short note above it says what the error means and which line to look at.

Some problems come with new numbers every time. Type your answer and press Check. If it is not right, you can try again, open a hint, or see the worked solution done with your own numbers. If you make a common mistake, the reply says what went wrong. Then press New numbers for another one, as many times as you like.

In the formatting toolbar, the button puts a small working practice problem in your text. Change its numbers, formulas, question and solution, and press Preview to try it.

A lesson, problem or lab can carry hints. Stuck? Show a hint opens the first one, and each press opens one more, so you take only as much help as you need. Hide the hints puts them away again.

Many problems have a Check your answer box under the question. Work the problem out on paper, type your number, and press Check: you are told at once whether it is right, and the answer itself stays hidden. A small difference from rounding still counts as right, and you can type numbers like 2.7e-3 or 2.7 x 10^-3.

The questions at the end of a lesson keep their answers closed. Try the question first, then press Show the answer under it to check. Each question opens on its own, and Hide the answer closes it again.

To add hints to your own text, start each one on a new line with !hint and a space, like !hint Start from v = u + at. Hints written one after another open one at a time. Put the answer under the hints on a line that starts with !answer, like !answer v = 20 m/s. It stays hidden until the reader presses Show the answer. Start the next question on its own line, so its hints and answer stay with it. For an answer box, write a line like !check Resultant = 11.4 N, one for each number to check. A tolerance of your own goes at the end: (±2%) or (±0.5).

A note is reading material written by a teacher: theory, diagrams, pictures in the text, worked examples and Python you can run. Find them on Notes. Print one or save it as a PDF from its page.

Notes can be shared into a class, a course, a group, or with named students. A teacher can press Compile into a Note on a course to gather every lesson's theory and pictures, with its problems, labs and quizzes, into one new note, then choose what to keep.

A binder keeps notes on one topic together, in your order, like a playlist for reading. Press + Binder on any note. Your binders are on My binders, and only you can see them.

Move notes up or down, read them one after another, and press Print / Save as PDF for one document with a cover and a contents page. A binder holds up to 50 notes, and you can keep up to 30 binders.

Many lessons have a simulation built in: a graph or a moving picture with sliders. Move a slider, or type an exact value in its box, and the graph, the formula and the numbers beside it change at once. Play and Pause control one that moves, and Reset puts everything back.

Below the graph is the Python that draws it, with the values from the sliders filled in. Run this code opens it in the Python editor, where you can change it and run it yourself.

Lessons, problems and notes can also hold a live simulation from PhET, Desmos or GeoGebra, right in the text. In the formatting toolbar, the simulation button takes a link from one of those three sites.

The same button's Build one with sliders puts a small working simulation in your text. Change its sliders, formulas and drawings, and press Preview to see it work as you go. If something is wrong, the preview lists what to fix.

Teachers can also upload their own simulation as one HTML file, for a lesson or a problem. It runs in a sealed frame: it can draw and respond to clicks, but it cannot read anyone's account or anything else on the site.