WEBVTT
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Taking Apart
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In this video, we’re going to learn how to count to find how many objects are in one part when we break apart a group of up to 10 objects into two parts.
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This boy is a classroom helper.
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It’s his job to look after all the pencils on each table in his classroom.
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And we can also see a pot of 10 pencils.
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The helper is asking for four pencils.
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Let’s give him four pencils.
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We’ll need to take them out of the pot.
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We’ve given out classroom helper four pencils.
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How many are left in the pot?
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Did you count them correctly?
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There are six pencils left.
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We had 10 pencils in the pot to begin with.
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The class monitor took four pencils away and there were six pencils left in the pot.
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When we take objects away from a group, we’re subtracting.
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The whole amount or the number of pencils we had to start with was 10.
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If we break this number apart by taking away four, we’ll have six pencils left in the pot.
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So we can say that 10 take away four is six.
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We could do the same using a cube train or counting blocks.
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This cube train has been broken apart.
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How many cubes are there altogether?
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Let’s count them: one, two, three, four, five, six, seven, eight, nine.
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This is the whole amount or the amount of cubes we used to make our cube train.
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We can see that the cube train has been broken apart.
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Let’s count how many cubes were taken away: one, two, three, four.
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We had nine cubes to start with; this is the whole amount, and we broke the whole amount apart.
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We took away four cubes.
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How many are left?
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Let’s count.
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There’s one, two, three, four, five, so we can say nine take away four is five.
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In this video, we’re going to practice answering some questions where we need to break apart a group of up to 10 objects.
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And we’re going to use part–whole models and cube trains to help us count how many objects there are in one part.
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So let’s try some questions now.
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Complete the following.
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When I take apart nine, I get five and what.
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In this question, we’re shown nine apples, and we can see that the group of apples has been taken apart to make two groups.
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We’re told that one of the parts or one of the groups has five apples, and we have to work out how many apples are in the other part.
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Let’s record what we know using our part–whole model.
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We’re told that there are nine apples.
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This is the whole amount.
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We’re told that once the apples have been broken apart, one of the part has five apples and we have to work out how many are in the other part.
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Let’s count how many apples are in each part.
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This part has one, two, three, four apples.
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If this part has four apples, then this part must have five apples.
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When I take apart nine, I get five and four.
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A cube train has eight cubes.
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If five of them are red, how many green cubes are there?
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In this question, we’re shown a cube train with eight cubes.
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So this is our cube train.
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And we can see that the cube train has been broken into two parts.
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We’re told that five of the cubes are red, but we’re not told how many green cubes there are.
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Let’s write this information in our part–whole model.
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We know the cube train has eight cubes, and we know the red part has five cubes.
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Let’s count how many green cubes there are.
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There’s one, two, three.
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The green part has three cubes.
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If a cube train has eight cubes and five of them are red, then three of them must be green.
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Chloe has seven dolls.
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She puts her dolls into two boxes.
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Complete the following sentence.
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There are three dolls in one box and what dolls in the other.
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Are there four, three, or five?
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In this question, we’re told that Chloe has seven dolls and she puts her dolls into two boxes.
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We’re also told that there are three dolls in one box, but we’re not told how many dolls are in the other.
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We have to choose from three possible answers.
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Are there four dolls in the other box, three, or five?
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Let’s use a part–whole model to help us think about the problem.
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We know Chloe has seven dolls and there are three in one box, and we’re trying to work out how many dolls there are in the other box.
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Let’s use the picture of the seven dolls to help us.
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We can cross out the three dolls that Chloe has already put away in a box.
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Then we can count the number of dolls that are left.
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There’s one, two, three, four.
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Now we can complete the sentence.
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There are three dolls in one box and four dolls in the other.
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The missing number is four.
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Complete the following sentence.
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When I take eight apart, I get three and what.
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This question is all about breaking apart our cube train.
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We’re told that our cube train has eight cubes, and we have to break it apart into two parts.
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We’re told that one of the parts has three cubes, so let’s count out our three cubes: one, two, three.
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Now we can count the number of cubes in the other part.
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One, two, three, four, five.
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Now we can complete the sentence.
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When I take eight apart, I get three and five.
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The missing number is five.
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Choose two numbers to complete the following sentence.
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Nine is what and what.
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And we’re given three numbers to choose from: three, six, and five.
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Our model shows nine circles.
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Let’s shade three of them.
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One, two, three.
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We had nine circles, and we shaded three of them orange.
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Let’s count how many circles are left.
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One, two, three, four, five, six.
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We can complete the sentence.
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Nine is three and six.
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The two numbers we needed to complete the sentence are three and six.
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What have we learned in this video?
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We have learned how to find how many objects are in one part when we break apart a group of up to 10 objects into two parts.