lesson
Updated 6 days ago · 2 views
Imagine a big jar full of shiny marbles on your teacher's desk. You want to know how many marbles are inside, but you do not have time to count every single one!
To make a smart guess without counting one by one, we make an estimate. An estimate is a quick guess that is close to the real amount.
Friendly Benchmarks: 5 and 10
A benchmark is a helpful group size that you already know by sight, like the 5 fingers on one hand or all 10 fingers on both hands.
📊Interactive diagram
When you look at a small pile, ask yourself: does it look closer to 5, or is it closer to a full 10?
What happens when you see a much bigger pile of up to 50 items?
Counting by Tens
To estimate larger groups, we mentally picture our benchmark group of 10 and see how many times it fits in the pile.
📊Interactive diagram
If you see about three groups of 10, your estimate is 30. If you see about four groups of 10, your estimate is 40.
Remember, an estimate does not need to be the exact number. It just needs to be close enough to give you a helpful idea!