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Reading and Writing 18, 19, and 20
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In this video, we will learn how to read, write, and model the numbers 18, 19, and 20.
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When we’re counting more than 10 objects, it can be really tricky.
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It’s easy to lose your place and forget which objects you’ve counted and which ones you haven’t.
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Can you count the number of gel pens?
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A good way to count large groups of objects accurately is to place them in groups.
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When we’re counting more than 10 objects, we could put them in a group of 10 and some more.
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Let’s try that.
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They look much easier to count now.
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We’ve made a group of 10 and some more.
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Let’s count the pens which are not in the group of 10, one, two, three, four, five six, seven, eight.
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What number does 10 and eight make?
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10 and eight more is 18.
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If we add one more pen, we’ll have a group of 10 pens and nine more.
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What number does 10 and nine make?
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10 and nine is 19.
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If we add one more pen, we’ll have two groups of 10.
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10 and 10 makes 20.
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Another way to model numbers greater than 10 is to use ten frames.
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When a ten frame is full, we know it contains 10 objects.
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This ten frame contains 10 counters, and the other frame has eight counters.
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10 and eight is 18, 10 and nine is 19, and two ten frames or two 10s make 20.
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Let’s practice counting groups of 18, 19, or 20 objects with some questions.
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Write the number of apples.
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In this question, we need to count the number of apples and then write the number.
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We know this is a group of 10 apples.
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It looks just like a ten frame.
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Now we need to count how many more apples there are, one, two, three, four, five, six, seven, eight.
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10 and eight make the number 18.
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10, 11, 12, 13, 14, 15, 16, 17, 18.
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The number of apples is 18.
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Which of the following models represents 19?
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We’re shown four different models, and each model represents a number.
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We’re looking for the model which shows the number 19.
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Let’s look at the first model.
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There are two ten frames, and each ten frame is full of counters.
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Which number does 10 and 10 make?
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10 and 10 is 20.
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This model represents the number 20.
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This is not the one we’re looking for.
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We’re looking for the model that represents the number 19.
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Let’s look at our second model.
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The first ten frame is full; it has 10 counters.
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And the second ten frame has eight.
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10 and eight makes the number 18.
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This is not the model we’re looking for either.
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Let’s try the third model.
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This model has a 10 and nine more.
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What number does 10 and nine make?
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10 and nine is 19.
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So this is the model which represents the number 19.
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10 and nine more is 19.
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The final model represents the number 17 because 10 and seven more is 17.
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We found the model which represents the number 19.
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10 and nine more is 19.
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How many wooden sticks are there?
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We’re shown two bundles of wooden sticks.
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Before we can tell how many sticks there are altogether, we need to work out how many sticks there are in each bundle.
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Let’s count them, one, two, three, four, five, six, seven, eight, nine, 10.
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Both bundles contain the same amount of wooden sticks.
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There are 10 sticks in each group.
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What is 10 and 10?
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10 and 10 makes 20.
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10 and 10 makes 20.
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There are 20 wooden sticks.
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What have we learned in this video?
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We have learned how to read, write, and model the numbers 18, 19, and 20.