A mystery box just arrived
Nobody knows how heavy it is, and you are not allowed to peek inside. All you have is a balance scale and a sack of weights.
Make the scale level. Then work out what the box must weigh.
- Watch How to Play to learn the trick.
- Balance the scale and type the weight of the box.
- Open 20 boxes to unlock the Prize Vault.
My badges
0 of 20 boxes opened
Teacher note
This game builds the big idea behind equations: a level scale means both sides are equal. Students find the unknown by adding weights to either pan. Putting a weight on the box's own pan works like subtraction, and from Level 2 on that move is required.
A wrong answer ends the round and that box does not count, so guessing does not pay. The game then shows how the pans add up. Students need 20 correct boxes across four levels to unlock the prize video. When the video ends, all progress resets to zero. Progress is saved in the browser on that one Chromebook only. No supplies are needed.
How to play, and why
- The sack dumps out weights. Each one has a number.
- Drag weights onto the pans. You can also click a weight, then choose a pan.
- The heavy side drops. Make the scale level.
- When it is level, both sides weigh the same. Use that to find the box.
- Type your answer and open the box. A wrong answer sends the box away, so think first.
The Prize Vault is locked
The Prize Vault is open
You opened every box. Watch your prize video! When it ends, your boxes and badges go back to zero so you can earn them again.