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Learn how to collect information and turn it into colorful charts and graphs.
Imagine you have a giant bag of mixed candy. How could you show your friends exactly which flavors you have without dumping the whole bag on the floor?
Data is just a fancy word for information! When we ask questions like 'What is your favorite color?' or 'How many pets do you have?', the answers we get are our data. To keep track of it, we use tally marks. We draw one line for each answer: . When we get to five, we draw a diagonal line across the four lines like this: . This makes it easy to count by fives! We can organize data into up to four different groups or categories to keep things neat.
Quick Check
If you see the tally marks and , how many items did you count in total?
Answer
7
A picture graph uses small pictures or symbols to show how many items are in each category. If we are counting apples, we might draw a small red apple for every one we find. It is very important to look at the key. The key tells us what each picture stands for. In our graphs today, one picture will equal item. Picture graphs are great because you can see which group is the biggest just by looking at which row is the longest!
Let's make a picture graph for a basket with Apples and Bananas. 1. Write the names 'Apples' and 'Bananas' on the side. 2. For Apples, draw small circles: . 3. For Bananas, draw small circles: . 4. You can clearly see there are more apples because the row is longer!
A bar graph is like a picture graph, but instead of drawing icons, we use solid colored bars. The side of the graph has a scale with numbers like . To show how many items are in a category, we color in the bar until it reaches the correct number on the scale. Bar graphs make it very easy to compare different groups quickly. You can have bars that go up and down (vertical) or side to side (horizontal).
A class voted on pets. kids chose Dogs and kids chose Cats. 1. Look at the bar for 'Dogs'. It stops at the line for the number . 2. Look at the bar for 'Cats'. It stops at the line for the number . 3. To find the total number of kids, add them: .
Quick Check
On a bar graph, if the bar for 'Blue' ends at the number 6, how many people chose Blue?
Answer
6
Graphs help us answer 'how many more' or 'how many less' questions. To find out how many more one group has than another, we use subtraction. We take the bigger number and subtract the smaller number. For example, if there are red cars and blue cars, we calculate . This tells us there are more red cars than blue cars. You can also see this on the graph by looking at the empty spaces between the ends of the two bars.
A graph shows kids like Popcorn and kids like Pretzels. 1. Identify the numbers: Popcorn = , Pretzels = . 2. To find 'how many more' like popcorn, subtract: . 3. To find 'how many fewer' like pretzels, it is the same answer: . 4. To find the total number of snackers: .
What do we call the information we collect for a graph?
If a picture graph shows stars for 'Team A' and stars for 'Team B', how many more stars does Team A have?
In a bar graph, the height of the bar tells you the number of items in that category.
Review Tomorrow
Tomorrow morning, look around your room and try to count two types of things (like shoes and books). How would you draw a quick bar graph for them?
Practice Activity
Grab a handful of colorful cereal or blocks. Sort them into colors, make tally marks for each, and then draw a picture graph where one circle equals one piece!