Video: Reading Bar Graphs

In this video, we will learn how to read bar graphs with unit scales and solve put-together, take-apart, and compare problems.

16:44

Video Transcript

Reading Bar Graphs

In this video, we’re going to learn how to read bar graphs. And we’re going to learn what we can see to solve problems. Now, if you wanted to read at home or you were given some reading time in school, what would you pick up? Maybe you’d choose a good book or maybe a newspaper. But I’m guessing that one thing you wouldn’t think about reading is a bar graph. But this video is all about reading bar graphs. And by the end of this video, we’re going to see that bar graphs tell a little bit of a story. And just like a newspaper, they also give us information. So, whilst you still might not choose them for your reading time, let’s see how we can read a bar graph.

Here’s an example of a bar graph. What story or information does it give us? Now, whenever we start to read a bar graph, we need to look at each of the parts that make it up. Let’s label them as we go along. At the top, we’ve got a title. Not all bar graphs have one of these, but it’s really helpful if they do. Most popular ice cream flavors at Gino’s. Our title tells us what this graph is about, what story it’s going to tell us. It’s going to tell us how popular different ice cream flavors are, and it even tells us what shop we’re talking about.

What other parts can you see on this graph? Can you see there’s a line going up the side of the graph? We can call this the 𝑦-axis. But in this video, we’re not gonna be too worried about this; we’ll just call it the scale because we can see a scale of numbers labeled on there, and it goes from zero all the way up to 12. And can you see if you look carefully at this scale it increases in ones, doesn’t it? All of the bar graphs in this video are going to have a scale that goes up in ones, but we need to always look really closely at the scale because it doesn’t always increase in ones. Now if we turn our heads slightly, we can see how this scale has been labeled. It says, number of sales yesterday. So, this scale is where we’re going to find out how many ice creams have been sold, how popular they are.

At the bottom of our graph, we can see another line. We can call this the 𝑥-axis, but again, we’re not gonna worry about this in this video. Instead, we’re just going to look at how it’s being labeled. And we can see all of different flavors of ice cream that this shop has sold. We could say these are the different categories. We’ve got raspberry ripple, strawberry surprise, blueberry boost, and caramel crunch. And then, for each one of our categories or flavors of ice cream, we can see some bars. And because we’ve read all the different bars of a graph, we know what these bars are going to tell us. They’re going to tell us the number of sales of a particular flavor of ice cream in Gino’s yesterday. And, of course, this is going to help us find the most popular flavors of ice cream.

So that’s the story behind the graph. Now, let’s try reading it for information. Which is the most popular flavor of ice cream? Well, because our graph is all about the number of sales, we can say that the most popular ice cream is going to be the one that has sold the most. It’s going to be the flavor with the tallest bar. Can you see which flavor this is? It’s this bar here, the one that represents strawberry surprise. And if we take a ruler to the top of our bar or use a finger to trace across, we can draw a line all the way across to our scale. And this tells us the number of strawberry surprise ice creams that were sold. It was 11.

And of course, if we can find the most popular ice cream flavor, we can also find the least popular. Which bar is the shortest? Well, of course, it’s this one on the end, isn’t it? Caramel crunch seems to be least popular. And again, if we draw a line all the way across from the top of our bar until we hit the scale, we can see that Gino only sold one caramel crunch ice cream.

Do you know we can do much more than just spotting the most and the least popular? We could solve lots more problems using this bar graph. Let’s imagine Gino’s set himself a target. He knows that he hasn’t sold enough blueberry boost ice cream, and he wants to sell more. In fact, he wants to sell as many blueberry ice creams as he has done raspberry ripple. And so, he asks himself, “what was the difference between the number of raspberry ripple ice creams I sold and the number of blueberry ice creams?” Can you see how he’d find the answer? He would look at the raspberry ripple bar and draw a line all the way across to the scale to work out how many he’d sold, and the answer is eight.

Now sometimes when we’re dealing with bar graphs, it can be helpful to make a note of the number we’ve just read above the bar. It’s just a way to make sure we don’t forget it and we don’t have to keep looking across at the scale. We’ve already looked once, and we’ve made a note of it.

Now we’ll do exactly the same with the blueberry boost. We’ll start at the top of the bar and go all the way across until we hit the scale. Gino sold three blueberry boost ice creams. So, what’s the difference between the two flavors of ice cream. We can find the answer using subtraction. Eight take away three equals five. In other words, Gino’s going to need to sell another five blueberry boost ice creams until he reaches the same level as those raspberry ripples.

Let’s imagine that Gino sits down at the end of the day and says, “how many ice creams did I sell altogether?” He can also find out this piece of information from the graph. To do this, he needs to read each of the bars. As we’ve just found out, he sold eight raspberry ripple ice creams. At the start, we read the number of strawberry surprises, didn’t we? We said that was 11. Then, we’ve just read three blueberry boosts and again, do you remember, one caramel crunch. So, can you see what he needs to do to find the total number of ice creams he sold? He needs to add together eight, 11, three, and one. We know that eight plus 11 equals 19. Now, if we look for numbers that make a pair really quickly, it might make sense to add the one on the end first. 19 plus one equals 20. And then if we add the three, we get a total of 23. Gino sold 23 ice creams altogether yesterday.

So from a small bar graph, we’ve got a lot of information, haven’t we? We’re going to answer some questions now where we have to use what we’ve learned about reading bar graphs. And as we do, what are the things we’re going to look for? We’re going to start by reading the title. And if there isn’t a title, we’re gonna look really carefully for a description of what the graph is about. We’re going to look at the scale and how it’s being labeled. These bar graphs are interesting, isn’t it? Because the scale goes horizontally from side to side. But don’t be confused if you see this. It’s still a bar graph; it’s just a different way of showing the information.

As well as looking at the numbers on the scale, we also need to look at how the scale’s been labeled. What do the numbers represent? And then finally, we’ve got the categories on this graph. There are three. And of course, the bars that go with them which we can use them to read the graph and to solve the problems. Let’s have a go at answering some questions then.

The Gotham Knights, the Metropolis Meteors, and Spartans won baseball games last summer. This bar graph shows how many games each team won. How many games did the Gotham Knights win?

In this question, we’re given a bar graph to look at. And we need to solve the problem by reading it. Now, this bar graph doesn’t have a title above it to tell us what it shows us. But we are given a description of what it’s all about in the question. We’re told that the Gotham Knights, the Metropolis Meteors, and Spartans all won baseball games last summer. Can you see on the graph where each team is mentioned? They’re at the bottom, aren’t they? Our next sentence is useful because it tells us exactly what our graph shows. The bar graph shows how many games each team won. And if we look at the side of the bar graph, we can see the title “Games Won.” And then there’s a scale up the side that increases in ones.

Now that we understand what our bar graph shows, we can answer the question. We’re asked, how many games did the Gotham Knights win? Well, it looks like we don’t have to worry about the other two teams, does it? This question is all about the Gotham Knights. We just need to look at this first bar here. And the height of this bar is going to show us how many games the Gotham Knights have won. And we can find the answer by going all the way to the top of the bar and then either drawing a line with a ruler or putting our finger and tracing straight across until we hit the scale. The bar is level with the number 14. We know that these numbers represent the number of games won. And by reading the bar across like this, we can see that the number of games that the Gotham Knights won was 14.

Some students ate bananas, strawberries, or kiwis at a picnic. The given bar graph shows how many students ate each type of fruit. How many more students ate strawberries than bananas?

In this question, we’re given a bar graph to read, and it’s all about a school picnic. We’re told that the students at the picnic ate bananas, strawberries, or kiwis. We’re also told why this bar graph is there for. It shows us how many students ate each type of fruit. And there are two types of fruit that we need to think about particularly here because we’re asked how many more students ate strawberries than bananas.

This is a comparing question. We need to compare the bars that show the number of students that ate strawberries with bananas. And if we look at the labels at the bottom of our graph, we can see that these are the first two bars. And if we look at the side of our graph, we can see a scale that goes up in ones, and it’s labeled “Number of Students.” This is where we’re going to find the information from that we need. So, let’s see how many students ate each type of fruit.

First, the bananas. So, we’ll go all the way to the top of the bar that represents bananas. And we’ll either use a ruler or we’ll trace across with our finger until we hit the scale. It’s the same height as the number six. So, we can say six students ate bananas. And we could label this bar with a six just to remind us. And if we do exactly the same with the bar that represents strawberries, we can see that 10 students ate strawberries on the picnic. You see, it’s level with the number 10. So to find out how many more students ate strawberries and bananas, we can just work out a subtraction. 10 take away six equals four. And so, we can say that the difference between 10 and six is four. Four more students ate strawberries than bananas.

You know, there’s another way we could have solved this problem. Because we know that each line on the graph is worth one, we could have counted how many jumps it takes to get us from the top of the bar that represents bananas to the one that represents strawberries. The difference is one, two, three, four. So that’s interesting, isn’t it? It’s a way to find the answer without actually reading across to the scale on the side. Well, we’ve used two different methods, and we found the same answer both times. At the picnic, four more students ate strawberries than bananas.

Daniel needed some school supplies. He used tally marks to record his requirements. Which of the following bar graphs represents the tally chart?

This problem tells us about someone who needs some supplies for school. And we’re told that he used tally marks to record what he wanted. And we’ve shown these tally marks in a tally chart. Do you remember how tally marks work? Each mark represents one more. And in this case, it’s one more object that Daniel needs. Instead of recalling them like this, where we have lots and lots of individual marks, it can be very difficult to count them; we’d be counting each one separately. Instead, what we do is as soon as we get to a multiple of five, one, two, three, four, and then the fifth one, we make into a block of five. So we have six, seven, eight, nine, 10. And so, by recording tally marks in blocks of five, it makes it much easier to count.

Let’s start then by counting how many of each type of supply Daniel needs. Firstly, the notebooks. We can see one group of five and then two more tally marks. And five plus two more is — seven. The next box we can see how many pens Daniel needs. And there are two groups of five tally marks, so that makes 10 pens. Next, we’ve got an eraser or a rubber. And we can see four individual tally marks, so that’s four erasers that he needs. And finally, on the end, we’ve got some backpacks. And we can see that he needs two backpacks, probably to told all this equipment in.

Next, we’re shown two bar graphs. And we’re asked which of the following bar graphs represents the tally chart. In other words, which one shows that Daniel is going to need seven notebooks, 10 pens, four erasers, and two backpacks? Let’s read them to find out. We’ll start by looking at the first bar graph. And we could look at the first bar on it, which we can see represents the number of notebooks that Daniel needs. If we put our finger on the very top of this bar and draw a line all the way across to the side, we can see that it reaches the number six. We can tell by the label that this represents the number of supplies Daniel needs. This bar graph tells us that Daniel needs six notebooks. But this is wrong, isn’t it? We know Daniel needs seven notebooks.

Let’s check the second bar graph and see if this is any better. And again, if we go to the top of the first bar and read across, this time we can see the correct answer. Daniel is going to need seven notepads. It looks like our second bar graph is correct, but let’s just read the other bars. They tell us that Daniel is going to need 10 pens, which is correct. He’s going to need four erasers, which is also correct. And if we look at the height of the final bar, we can see that he’s going to need two backpacks. Although the tally chart in the bar graph are two different sorts of things, they both show the same information and the bar graph that represents a tally chart is the one that shows that Daniel needs seven notebooks, 10 pens, four erasers, and two backpacks.

What have we learned in this video? We’ve learned how to read bar graphs. We’ve also learned to apply what we’ve found out to solve problems.

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