Coin flip.

How to flip a coin in 3 steps

1. Press Flip, or the Space bar. The coin tosses, turns in the air and lands on heads or tails. The result is written under the coin, so nobody has to squint at it.
2. Choose a mode. Single flip is one toss at a time. Best of 3 and Best of 5 keep the score and name the winner the moment one side gets there.
3. Flip several coins. Set Coins from 1 to 10 and press Flip once. You get a count of heads and tails, and the tally keeps adding up until you press Reset.

Press F or Full screen to put the coin on a projector or a TV, with a dark background that reads from the back of the room. Esc brings you back. Gold, silver or copper is up to you; the odds stay the same.

Is the coin flip fair?

Yes. Each flip asks your browser’s cryptographic random source for one of two values, the same source websites use to make security keys. Heads and tails each get exactly 50%, and no flip remembers the one before it. The animation plays the result out; it never decides it.

A real coin is not quite this fair. Studies of real tosses have found a slight lean towards the side that started face up, about 51%. This one has no side to start on, so it has no lean.

Ideas for classes, meetings, games and events

• Who goes first. One team calls it in the air. Heads, they start; tails, the other team does. Full screen makes it official.
• Settle a tie. Two ideas, two names, two restaurants. Flip once and move on with the day.
• A quick group decision. Best of 3 keeps a small argument short. Best of 5 gives a close call a little more drama.
• Probability in maths class. Flip 10 coins at a time and watch the tally settle towards 50/50 over a few hundred flips, while any single run can still go 7 to 3. For ages 13 and over.
• Team games. Flip for the first move, a bonus turn or a penalty. Everyone sees the same coin on the big screen.
• Streams and video calls. Share the tab and let the chat watch the coin land, instead of taking your word for it.

When one coin is not enough

A coin picks between two things. When the room should choose between more, or every voice should count, run a live poll in RiLiFi. People vote from their phones and the bars grow on the big screen. See the live poll.

To pick a name instead of a side, spin the random name picker wheel. To roll for a number, use the dice roller or the random number generator.