How it works
To search a list, check one item at a time, in order.
Stop as soon as you find what you want. There is no need to open the rest.
If you reach the end and it is not there, it is not in the list, because every box was checked once.
In order, no box is opened twice and none is missed.
Worked examples
Find it, then stop
- Jonah wants his star sticker. Bo opens box 1: a leaf. Box 2: a moon. Box 3: a shell. Box 4: a kite.
- Box 5 holds the star, so Bo stops.
- Boxes 6, 7 and 8 never need opening. Bo opened 5 boxes.
Count the boxes
- Jonah wants the shell. It is in box 3.
- Bo opens box 1, box 2 and box 3, and stops.
- He opened 3 boxes.
Not in the list
- Jonah wants a rocket sticker, and Bo opens every box from one to eight, in order.
- None of them holds a rocket.
- Every box was checked once, so the rocket is not in the list. Bo opened 8 boxes.
Going round in circles
- Jonah opens box five, then box two, then box five again.
- Opening at random can open one box twice and miss another.