lesson

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Look at all these shiny stars scattered on your desk! How can we find out exactly how many there are without guessing?
To count accurately, we use one-to-one correspondence, which means we touch one object and say exactly one number name.
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The Cardinality Principle states that the final number you say represents the total quantity of the entire collection.
For example, if you count "1,2,3,4,5,6,7", the last number tells you there are 7 items altogether.
For example, counting "1,2,3,4,5,6,7" means there are 7 items altogether.
What should you do when you have even more items, like 7 or 8 buttons?
Line Them Up
When items are in a straight row, always count from left to right so you never lose your place.
Touch each button once, say the number out loud, and keep your finger steady.
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What happens if your items are not in a neat line, but jumbled up in a messy pile?