Hello young mathematicians! Today we are going to learn how to organize information. Information that can be represented by numbers is considered as data. One method of collecting data is using tally marks.
Imagine you are watching cars pass by. Each time a vehicle arrives, to represent the type and the arrival, a segment of a line (/) is marked. The symbol "/" is called a tally mark.
To make counting super fast, we group them into fives! We mark the 5th item by drawing the 5th tally mark across the four tally marks that had been marked before. Therefore, a crossed group represents 5 items. It is easier and quicker to count the tally marks that have been separated into groups of five than to count them one by one.
Example: Vehicles at the Office
| Type of Vehicle | Tally Marks | Number of Vehicles |
|---|---|---|
| ๐ Car | ๅ ๅ ๅ | 15 |
| ๐ Van | / / / / | 4 |
See? Counting by 5s makes 15 cars super easy to see! 5, 10, 15!
Now that we know how to collect data, let's draw it! Collected data can be represented by using tables or picture graphs.
A representation of data using symbols is called as a picture graph. The number of data represented by a symbol in the picture graph should be indicated. Sometimes, if we have lots of items, we can't draw them all. Instead, we let one symbol represent many items! We can also use parts of a symbol, like a half or a quarter, to represent smaller numbers.
Example: Students in a Montessori
Let's represent 4 students by a full circle ๐ก.
| Year | Number of Students | Symbols (Picture Graph) |
|---|---|---|
| 2009 | 20 | ๐ก๐ก๐ก๐ก๐ก (20 รท 4 = 5) |
| 2010 | 18 | ๐ก๐ก๐ก๐ก๐ (4 fours and a two) |