Remember: To search a list, check one item at a time, in order. Stop as soon as you find it, and if you reach the end, it is not in the list.
Read and answer
Read the story, then answer.
Which box?Jonah has eight boxes of stickers in a row, numbered one to eight. He needs his star sticker for the show that night, but the boxes are shut, and he cannot remember which one holds it. He opens box five, then box two, then box five again, going round in circles. Bo tilts his head. Then Bo starts at box one and opens the boxes in order. Box one holds a leaf, box two a moon, box three a shell and box four a kite. Box five holds the star, and Jonah whoops. Stop! There is no need to open boxes six, seven and eight. Later Jonah wants a rocket sticker, and Bo opens every box from one to eight. There is no rocket, so Bo says it is not in this list.
1
Jonah opens box five, then box two, then box five again. Why is that a problem?
He is opening the boxes in orderHe opens one box twice and may miss anotherThe boxes are open already
2
Bo opens the boxes one at a time, in .
circlesa hurryorder
3
When you find what you want, you can stop looking.
TrueFalse
4
Bo goes in order and stops at the star. The star is in box five. How many boxes does Bo open?
458
5
Jonah now wants the shell. Bo goes in order. How many boxes does Bo open?
315
6
After box four, Bo should open box one again to be sure.
TrueFalse
Search in order
7
Put Bo's search plan in order.
Open box one
If not, open the next box
Ask: is this the one?
If no boxes are left, say it is not in the list
If it is, stop looking
8
Join each idea to what it means.
1find it
2every box checked and it is missing
3open the boxes in order
4count the boxes opened
Ashows how many it took
Bit is not in the list
Cstop looking
Dno box opened twice or missed
9
Mix-up to fix: Bo opens boxes 1, 2 and 3, finds no star, and says the star is not in the list. What should he do?
Open box one againSay it again, but louderOpen the rest of the boxes before he says so
10
Jonah wants the moon. Bo goes in order and stops when he finds it. He opens boxes.
11
Stretch: Jonah wants a rocket sticker. Bo goes in order through all eight boxes and sees no rocket. He opens boxes before he can say it is not in the list.
12
Hide a coin under one of eight cups. Write how you would search for it: what you do first, next, and when you stop.
13
Draw eight boxes in a row and write the numbers 1 to 8 on them.
Scan the code at the top to mark this sheet on screenTake a photo of your answers or type them. It is marked for you automatically, and your score is kept.
Answer key · Set A
Jonah's sticker boxes
1He opens one box twice and may miss another Opening the boxes at random can open one box twice and miss another. In order, no box is opened twice and none is missed.
2order Checking in order misses none.
3True Bo found the star in box five, so there was no need to open boxes six, seven and eight.
45 He opens boxes 1, 2, 3, 4 and 5, then stops.
53 Box 1 holds a leaf, box 2 a moon, and box 3 the shell, so he stops at the third box.
6False Opening a box twice wastes time. Each box only needs to be opened once.
71, 4, 2, 5, 3 Open a box, ask, stop if it is the one, and go on if it is not. If you reach the end, it is not in the list.
81-C, 2-B, 3-D, 4-A Each idea is a job in a search: stop when found, say not there at the end, go in order, and count the boxes opened.
9Open the rest of the boxes before he says so One box, or three, is not the whole list. Check every box before you say it is not there.
106 The moon is in box 6, so Bo opens boxes 1 to 6.
118 He must open every box, boxes 1 to 8, before he can say the rocket is not there.
12Your own words: a grown-up reads it.
Mark each answer, count the right ones and write the score on the sheet.