Data and graphs
Imagine you have 25 classmates and each one tells you which ice cream flavour is their favourite.
25 answers. How do you turn that into a picture that tells the whole class which flavour wins?
Answer: a graph (or chart).
What a graph is
A graph is a picture that shows numbers so that you can compare them quickly.
Instead of reading 25 answers, at a glance you can see: 8 children want vanilla, 12 chocolate, 5 strawberry.
In second grade we learn three kinds of graphs:
- Tally chart — a simple list with tally marks.
- Pictograph — pictures instead of numbers.
- Bar chart — bars of different heights.
Why we need them
Graphs teach us two things:
- Find an answer — which is the biggest? the smallest? the same?
- Work out the difference — how many more? how many fewer?
A second-grader who can read a graph can answer questions without going back through the list.
What we will learn
In this topic we cover:
- How to record data with tally marks.
- How a pictograph works — where 1 picture = 1 (or sometimes 2 or 5).
- How to read a bar chart — bar height = the count.
- How to answer "how many" and "how many more" questions.
Summary
- A graph = a picture that shows numbers.
- In 2nd grade we use: tally chart, pictograph, bar chart.
- From a graph we read biggest/smallest and differences.
- A graph is faster than going through a list.