Counting with Lights: Binary Numbers

1. What your child learns and why

A computer records numbers with bits — “switches” that are on (1) or off (0). In this lesson your child sets four lamps worth 8 · 4 · 2 · 1 and discovers that they show 16 different numbers — from 0 to 15. The “magic” of zeros and ones becomes a rule they can check for themselves.

2. Three questions for dinner

• “Four lamps give 16 numbers. If we add one more lamp, how many will there be?” (32 — it doubles; it need not be exact, what matters is that they work it out)
• “Which lamp changes most often when we count? And which one least often?”
• “Which things in your day change often, and which rarely?”

3. 10 minutes together, no screen — counting on fingers

1. Every finger is a lamp: the little finger is 1, the ring finger is 2, the index finger is 4, the thumb is 8. The middle finger rests, folded away. A raised finger = “on”.
2. Show these together: 5 = little finger + index finger (1 + 4); 12 = index finger + thumb (4 + 8).
3. Say a number from 0 to 15 — your child shows it. Then swap: you show, your child reads the number.
4. Count slowly from 0 to 15. Ask: “Which finger works the most?” If fingers do not obey, use four paper cups (upright = on).

4. What success looks like

• Your child reads a number from four lamps (or fingers) and shows the number you name.
• They explain in their own words why there are exactly 16, and why the smallest lamp changes most often.

5. Common difficulties

• They read “1 0 1 1” as “one thousand and eleven” or add up the digits → “Every lamp is worth something different — 8, 4, 2, 1. Add up only the lamps that are on.”
• They write the values as 1, 2, 4, 8 from the left → “The smallest is on the right, like the ones in an ordinary number.”

Say: “It did not work the first time — what will you try now?” Avoid: “This is easy” or comparisons with other children.

6. Safety

The lesson is a simulator on the screen plus a hand. If your child asks for a real circuit with LEDs — only with you beside them, only a small battery (up to 4.5 V), a resistor in front of every LED; never from a wall socket, and do not open, charge or heat batteries.

7. Where to go next

Next lesson: DB-EL-07 “A ‘Time for Fresh Air’ Device for the Class” · Previous: DB-EL-05 “Night Light: Sensor + LED” · Idea: send each other secret numbers drawn with four circles.

You do not need to know the answer. Say: “Let's find out together.”