Coin, card, phone

The same koruna, three wrappers

A coin clinks. A card is quiet. A phone shows a number. Your head feels these are three different worlds. They are not. They are wrappers on the same agreement: koruna that someone honours.

The wrapper changes how easily you spend. A coin runs out and you see the bottom. A card has no bottom in your pocket — the bottom is on a parent’s account. A phone can spend without you getting up from the sofa. That is why today we train eyes, not payment magic.

Tereza has two ten-koruna coins in her pocket. She wants juice for 25 Kč. The coins are not enough — that is easy to see. Jakub holds a parent’s phone with a payment preview. The number 25 looks tiny. It is not tiny. It is still twenty-five of the same koruna, as if they clinked on the counter.

At the stall Tereza counts. At the screen Jakub clicks. Both paths end in the same agreement. The difference is who may confirm. A coin in a child’s pocket (when it is pocket money) is a different chapter from a card a parent carries in a wallet. A phone with a banking app is not a toy.

A wrapper is not another currency

A coin and a banknote are cash. You see them. You can lose them on a tram. Nobody asks for a PIN when you put a twenty on the counter — they ask if it is enough.

A card is an order: “take tokens from an account that belongs to an adult.” An account is not your game. A PIN is not a level code. A limit on a card is a brake set by a parent or a bank, not by you.

A phone can do both: pay like a card, or just show a game. What matters is telling a game from a wallet. A shop icon in a game is not the stall holder in the corridor. It is a path to a parent’s account, often saved in settings you do not know about.

The course does not teach you “how to pay by card on your own”. It teaches you to see the wrapper. When you get to Banker, the PIN and a lost phone will come. Today one sentence is enough: the same koruna, a different wrapper, different rules for who may say yes.

Jakub wants a cinema ticket for 120 Kč. Option A: six twenties on the counter — he sees he will have zero left. Option B: a parent taps a card — 120 on the display. Option C: a purchase in a game “a pass for 119.99” — almost the same number, a different wrapper, the same hit to the family’s tokens.

Tereza draws three boxes. In the first she writes “clinks”. In the second “beeps”. In the third “clicks”. Under each: who may. First — often me, from pocket money. Second and third — a parent. That is where the drawing ends. No account number. No photo of a card.

Why this right now

You are in the course Money with Martin, level 準備. You can write numbers in a notebook or a table, but the topic is money and decisions, not Excel formulas. The account, the card and the PIN belong to a parent. A child’s email does not belong here. Do not put pocket-money numbers on the network.

This is not the Sheets with Martin course. A table may help, but the mark of success is a decision, not SUM.

You will know this lesson by one sentence: A coin, a card and a phone are wrappers on the same koruna — a parent watches the card and a payment on the phone. When you can say it to a parent or a teacher, you have the core. The rest is practice, not magic.

準備 has to separate the wrappers first. Otherwise a game purchase later looks like “free, I never saw a coin”. Seeing the wrapper is the start of Shopper and of Banker.

Four things you will build from the course

The course has four small projects. You do not have to do them all at once. Today you add only what this lesson can do.

Workshop: a wrapper on paper

You will draw three wrappers. No account number, no photo of a card, no PIN. It is about words.

1. メモbook: headings Coin, Card, Phone. By each one, one sentence on how it looks different (clinks / beeps / clicks).

2. By the card and the phone add: a parent approves. By coins from pocket money: I decide up to the limit that applies at home.

3. Find at home (with a parent) one thing that is paid other than with a coin — a ticket, lunch, a subscription. Write only the name of the thing, not a price from the account.

4. Tell a parent: “I do not approve a card or a phone payment.” That is the whole message. No numbers on the network.

When you can name three wrappers and say “parent” by two of them, the workshop counts. If you think a click in a game is another world, go back to the ticket for 120 Kč. The number is the same. The wrapper lies to the feeling, not to the koruna.

Practice: who may say yes?

For each purchase, name the wrapper and the person who may confirm. Do not build a plan to get around a parent.

1. Juice 25 Kč, two tens in the pocket. Wrapper? Enough? Who decides?

2. A music-app subscription that renews on its own. Wrapper? Who may cancel?

3. A classmate: “Lend me the phone, I’ll just tap it at the machine.” What do you say?

4. A skin in a game for 89 Kč, a Buy button. Wrapper? Where does it reach, if a card is saved?

Now you 💪

Go through three checks. By each one, tick in your head: do I see it, or not?

1. I can name three wrappers: coin, card, phone.
2. I know a card and a payment on the phone belong to a parent.
3. I do not photo a card and I do not say a PIN even “just for a second”.

If something is missing, go back to the steps above. It is not a test for marks. It is a safety net, so you go on with certainty, not with a mess.

What to take from this lesson

• A wrapper changes the feeling, not the value of a koruna.
• Cash is visible. A card and a phone reach an adult’s account.
• A game with a Buy button is a phone wrapper, not a prize.
• A PIN, a card and a banking app are not lent out.
• 名前s in the examples (Tereza, Jakub) are made up. Do not put your number, email or photo here.
• Next lesson: When you can do this, go to the next lesson in the same level.

© 2026 Ing. Martin Polak / AlgoRhino · コンテンツ利用規約