Video Transcript
Word Problems: Adding Numbers up to
20.
In this video, we’re going to learn
how to solve addition problems with numbers up to 20. And we’re going to do this by
finding either a missing part or the whole. We’re also going to find out how to
solve addition problems where we have to compare. Here’s a word problem based on an
addition. The first thing we need to do with
it is to read through the problem carefully. Let’s try to imagine what it’s
describing as we read through the words.
There are 14 trucks in a traffic
jam. Eight are red and the rest are
blue. How many trucks are blue?
We know that an addition is where
two parts are added together to make the whole amount or the total. Now, what numbers do we already
know in this word problem? Do we need to find one of the parts
or the whole? Our first number tells us that
there are 14 trucks in the traffic jam. This is the total amount, so we
know the whole. And we also know what one of the
parts is. Eight of the trucks are red. So let’s write the number eight in
our part–whole diagram. Although we know how many trucks
are red, we need to find how many trucks are blue. In other words, we need to find the
other part.
To solve the word problem, we know
we need to find a missing part of this addition. Eight plus what equals 14. What do we add to eight to make a
total of 14? We could use a ten frame to
help. Here are eight red counters. How many more counters do we need
to get to 14? Let’s count on from eight. Nine, 10, 11, 12, 13, 14. We needed six more counters. Eight plus six makes 14. And now we can use this complete
edition to answer our problem. The number of blue trucks is
six.
All of the word problems we’re now
going to look at have got either a missing part or a missing whole. Let’s try to find them.
A group of fairies were flying
around a flower. After four more fairies joined the
group, there were 14 fairies in total. How many fairies were there at the
start?
This word problem doesn’t tell us
how to find the answer. So we’re going to have to read it
very slowly and carefully to work out what we need to do. The first sentence in our problem
tells us that a group of fairies were flying around a flower. Now, we could look at the picture
and think to ourselves, “That must be the group!”. But if we carry on reading the
problem, we can see that this first group is only part of the whole amount. And we know this because four more
fairies joined the group. So we start with a group and we
don’t know how many are in that group. And then four more fairies joined
the group.
We’re then told that after these
four more fairies joined the group, there are 14 fairies in total. This is the whole amount. And if we look carefully at our
picture, we can see that this is the amount that our picture shows. We can see four fairies wearing
green dresses. These are the four more that joined
the group. And if we look at the whole amount,
we can see 14 altogether. To solve the problem, we need to
find the missing part in this addition. What plus four equals 14.
Let’s use cubes to help us find the
answer. One way to make the number 14 out
of cubes is to take a group of 10 and then a group of four ones. 10 and four make 14. And because we know this number
fact, we can now solve the problem. We know what the missing part in
our addition is. Let’s put the number 10 into our
word problem to see if it makes sense. A group of 10 fairies were flying
around a flower. After four more fairies joined the
group, there were 14 fairies in total. Yes, this does make sense. We know that 10 plus four equals
14. And so the number of fairies that
were there at the start is 10.
Daisy planted seven roses and five
sunflowers in her garden. Choose the addition sentence that
shows this, using a question mark for the total number of flowers. Five plus what equals seven. Seven plus what equals 12. 12 plus five equals what. Seven plus 12 equals what. Or, seven plus five equals
what.
In this problem, we’re given a fact
using words. We’re told that Daisy, which is a
good name when we talk about flowers, planted seven roses and five some flowers in
her garden. We could use seven pink counters to
represent our seven roses and five orange counters to represent the five
sunflowers. We’re now told to choose the
addition sentence that shows this. Well, if we’re thinking about
adding together the number of roses and sunflowers, then each of these groups must
be part of the whole.
So to find the whole or the total
amount, we need to add the two parts together. In other words, seven plus five
equals what. And if we look at all our possible
addition sentences, we can see the one that represents this. The question mark represents the
total number of flowers. And the way we can find the total
number of flowers is by adding together seven and five. Perhaps you know what the total
number is, but the question doesn’t ask us to work the answer out. We just need to find the correct
addition sentence. And this is seven plus five equals
what.
Michael is two years old. Benjamin is one year older than
Michael. Madison is five years older than
Benjamin. How old is Madison?
In this word problem, we’re asked
to find the age of Madison. And if we read the word problem
carefully, we can see a fact that will help us. We’re told Madison is five years
older than Benjamin. But how old is Benjamin? If we look back through the word
problem, we can find another fact that can help us. Benjamin is one year older than
Michael. But wait a moment, how old’s
Michael? To find the answer, we’re gonna
have to go all the way back to the beginning. We’ll start with Michael’s age, and
we’re going to find out everybody else’s age along the way.
So, let’s start with Michael. We’re told that he’s two years
old. Let’s put a counter on our number
track to show Michael’s age. In our next fact, we’re told that
Benjamin is one year older than Michael. In other words, if we take
Michael’s age, which is two, and we add one more year to it, then we can find
Benjamin’s age. Two plus one equals what?
To find the answer, we could count
on one from Michael’s age on our number track. We just need to move our counter
one place. Two plus one equals three. So now we know Benjamin’s age; he’s
three years old. And now we can solve our final fact
because we’re told that Madison is five years older than Benjamin. Now we’ve just worked out, haven’t
we, that Benjamin is three years old.
So we know Benjamin’s age. And we know that Madison is five
years older than this. So if we add five and three
together, this will give us Madison’s age. Three plus five equals what? Let’s count on five more using our
number track. One, two, three, four, five. We’ve reached the number eight. Three plus five equals eight.
We’ve used two additions to solve
this problem. Two plus one gave us Benjamin’s
age, which is three. And then we took this answer,
three, and we added five to it to find Madison’s age. Three plus five equals eight. And that’s how we know Madison is
eight years old.
Let’s go over what we’ve learned in
this video. We’ve learned how to solve addition
word problems. We’ve learned how to find a missing
part or the whole.
