The big ideaTo find the biggest, look at each one in turn and remember the biggest so far.
How it works
To find the biggest, look at each one in turn. Bo can only peek at one tower at a time.
Bo keeps the biggest so far in his memory box.
Each time he asks one question: is this tower bigger than the box? If yes, swap it in. If not, the box stays the same.
When you run out of towers, the one in the box is the biggest.
What the box holds after each tower.
Example 1: The first towers
Tower one has four blocks, so Bo keeps four in the box.
Tower two has nine blocks. Nine is bigger than four, so Bo swaps it in.
The box holds nine.
Example 2: Keep the box
Tower three has three blocks.
Three is smaller than nine, so Bo keeps nine in the box.
Example 3: Swap again, and finish
Tower four has twelve, which is bigger than nine, so the box holds twelve.
Towers five and six have seven and five. Both are smaller, so the box keeps twelve.
No towers are left, so the biggest is twelve, tower four.
Example 4: A different row
The towers have 5, 8, 2, 6, 11 and 9 blocks.
Tower 1: the box holds 5. Tower 2 has 8, which is bigger, so the box holds 8.
Towers 3 and 4 have 2 and 6, which are smaller, so the box keeps 8.
Tower 5 has 11, which is bigger, so the box holds 11. Tower 6 has 9, smaller, so the box keeps 11.
The biggest is 11.
Words to know
memory box
Holds the biggest tower seen so far.
swap
Put a bigger tower into the box in place of the old one.
so far
Up to the tower you are looking at now.
biggest
The most blocks of all the towers.
Watch out
Do not stop after the first tower. Stopping early can miss a bigger one.
Do not pick the last tower you saw. It is not always the biggest.
A smaller tower never replaces the biggest so far.
Check every tower, even one that looks small.
Try it
The box holds 9 and the next tower has 12. Do you swap or keep?
The box holds 12 and the next tower has 5. Do you swap or keep?
The towers have 3, 7 and 4 blocks. What does the box hold at the end?
Is the last tower you look at always the biggest?
The towers have 6, 2 and 9 blocks. What does the box hold after tower 2?
Answers: 1. Swap · 2. Keep · 3. 7 · 4. No · 5. 6
Try at homeAsk a grown-up to lay six number cards face down. Turn them over one at a time. Keep only one card in your hand, the biggest so far, and swap it when you find a bigger one. At the end, say which is the biggest, then turn them all over to check!
For grown-upsPlay the Mission: lay six number cards face down. Your child turns them over one at a time, keeping only one card in hand, the biggest so far, and swapping it when a bigger one comes. At the end, they say which is the biggest, then you turn them all over to check.
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