Size of Everything

Hook 5 min

1. Press ▶ Tour and fly from a proton to the observable universe.
2. "How many powers of ten did we cross?" (About 42.) "How would you write the size of an atom without a hundred zeros?"

Explore 15 min

1. Pairs press ÷10 Smaller a few times and read each card: the size in scientific notation, written out, and the units.
2. Pairs zoom to five things they choose and record each size both ways.
3. Pairs open Compare and pick two things. The card divides by subtracting exponents. "How many of the smaller thing would line up to match the bigger one?"
4. Pairs try Place it and drag the pin for ten things. Aim for three stars.

Make sense 10 min

1. On the board: "A negative exponent means a small number, not a negative number. Where do you see that on the Zoom slider?"
2. Work a comparison together: 8 × 10² ÷ 5 × 10⁻³. Round each coefficient to one digit, then subtract the exponents. (About 2 × 10⁵.)
3. "The jump from a proton to an atom is empty on purpose. Why?" (Atoms are almost all empty space.)

Apply 10 min

1. Pairs open Write it. They slide the decimal point to turn standard form into scientific notation and back. The exponent counts the hops.
2. Rule check: "Hop left, the exponent goes up. Hop right, it goes down. Does the value change?"
3. Pairs who finish pick the comparison that surprised them most and explain it.

Exit check 5 min

On a card: "Write 0.00042 m and 93,000,000 mi in scientific notation. The universe is about 10²⁷ m and a proton about 10⁻¹⁵ m. How many times bigger is the universe?" (10⁴².) Cards that call 10⁻¹⁵ a negative size show who needs the slider again.