How Balance Scale teaches kids to find the heaviest box in fewest weighings
A parent guide to Tomorrow Kid’s Logic Lab Which Is Heaviest?—pan weigh → tilt → “I know which!”, optimal-weighings stars, ternary-split habit, and 8+ placement.
What Balance Scale is for
Tomorrow Kid’s Which Is Heaviest? world is Logic Lab’s tipping-scale puzzle (balance_scale). One identical-looking box is heavier. Kids put boxes on the left and right pans, weigh, read the tilt, then tap “I know which!” to name the heavy box—in as few weighings as they can.
Parent tip: say “split into three piles” once before they play. Left pan, right pan, and the ones you leave off the scale is the idea behind finding the heavy box fastest—without typing any code.
Where it lives
- Confirm the child’s age band reaches 8+ so Phase 4 Logic worlds are available (Logic Lab itself needs 7+ on Home)
- Open Logic Lab and tap the Which Is Heaviest? world (“One box is heavier — find it in the fewest weighings”)
- Place matching boxes on left/right pans, weigh, and watch which side tips
- When ready, tap “I know which!” and pick the heavy box
For the broader Logic Lab overview (age gate, world ladders, Today’s puzzle), see the Logic Lab ages 7+ guide. This article owns the Balance Scale / weighings deep-dive only.
Weigh → tilt → “I know which!”
Play runs in BalanceScaleGameView:
| Step | What kids do |
| --- | --- |
| Load the pans | Put identical boxes on left and/or right |
| Weigh | Read the tilt—which side is heavier |
| Decide | Tap “I know which!” and pick the heavy box |
| Stars | Scored vs optimal weighings ⌈log₃ n⌉ (subtitle shows “Weighings: N · best possible K”) |
After too many weighings, a calm struggle hint nudges them to think in threes. Stars still feed the familiar Sticker Book economy.
Why splitting piles helps (no typed code)
The fastest strategy is a ternary split: some boxes left, some right, some off the scale. One weighing rules out two-thirds of the candidates. Parents can name that habit without saying “algorithm”—kids discover it by trying.
That is distinct from:
- Higher / Lower (Guess My Number) — binary halving with “Higher ⬆️ / Lower ⬇️”, not weighings; see the Guess My Number guide
- Pass & Play Bug Hunt — two-player plan fixing; see the Pass & Play guide
- Today’s puzzle — one shared Home board per day; see the Today’s puzzle guide
A calm way to introduce it at home
- Confirm age band 8+ and open Logic Lab together.
- Clear one simpler world first (Robot Walk or Bug Hunt) so the list feels familiar.
- Open Which Is Heaviest?, weigh once, and narrate the tilt out loud.
- Let them tap “I know which!”—celebrate the stars even if weighings were not optimal.
- On a later session, ask “could three piles find it sooner?” and stop after one board.
What to try next
Keep Balance Scale as the “fewest weighings” stretch after simpler Logic worlds. Use Pass & Play when you want a shared Bug Hunt handoff, and Today’s puzzle for the daily Home ritual. Ready to try it? Open Tomorrow Kid → Logic Lab → Which Is Heaviest?