253 on the frame: two hundreds, five tens and three ones.
The big ideaTen tens make a hundred. The third row of the frame counts hundreds.
How it works
Ten ones make a ten, and ten tens make a hundred.
The third row of the frame counts hundreds. One bead there is worth a hundred, a whole box of marbles.
Each row is worth ten times the row below it.
A thousand is ten hundreds. Three rows show up to 999, so a thousand needs a fourth row, which bigger frames have.
Each trade makes a bigger group.A full tens row: ten tens, ready to trade for a hundred.
Example 1: Make three hundred
Slide three beads across on the hundreds row, the top row.
Leave the tens row and the ones row empty.
Three hundreds, no tens and no ones is 300.
Three beads on the top row: 300.
Example 2: Build 462
Four beads on the hundreds row.
Six beads on the tens row.
Two beads on the ones row.
Four hundreds, six tens and two ones is 462.
462: hundreds on top, then tens, then ones.
Example 3: Trade ten tens for a hundred
Start with 190: one hundred and nine tens.
Add one more ten: 190 + 10 = 200.
The tens row is full, ten tens.
Slide the ten tens away and one bead lands on the hundreds row.
Now it is two hundreds and no tens: 200.
190 + 10: the tens row is full.
Example 4: Marbles left over
Two boxes, five bags and three loose marbles are on the table.
Boxes are hundreds, bags are tens and loose marbles are ones.
Slide 2, 5 and 3 beads across.
That is 253 marbles.
Words to know
hundred
Ten tens. One bead on the third row of the frame.
thousand
Ten hundreds. It needs a fourth row, which this frame does not have.
trade
Ten beads on one row become one bead on the next row up.
hundreds row
The top row of the three-row frame.
Watch out
A row holds one digit. Ten tens on the tens row must trade for one hundred.
An empty row is a zero. In 304 there are no tens.
Three rows show 0 to 999. A thousand is told and drawn on this frame, not worked.
Ten tens make a hundred, not a thousand. It is ten hundreds that make a thousand.
Try it
How many tens make one hundred?
What is 190 + 10?
Four hundreds, six tens and two ones. Which number?
What is the biggest number three rows can show?
Answers: 1. Ten · 2. 200 · 3. 462 · 4. 999
Try at homeAsk a grown-up to help you find something small, like dried beans or paper clips. Make a pile of ten, then another, until you have ten piles, and that is one hundred! Put them in a bowl to see how big a hundred looks.
For grown-upsFind something small, like dried beans or paper clips, and make ten piles of ten together. That is a hundred. Ten of those would make a thousand, but only to talk about.
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