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