43
Diagrams (charts)
Textbook, pp. 200–202
GoalKnow the kinds of diagrams (bar, line, pie); show and read data in a diagram.
New words
diagram (chart) · diagrammabar chart · ustunli diagrammaline graph · chiziqli diagrammapie chart · doiraviy diagramma
Explanation
A diagram shows data clearly. In a bar chart each value is a bar height and values are easy to compare. A line graph shows change over time, for example the temperature during a week. A pie chart shows the parts of a whole: the whole circle is 100% or 360°, and 25% is a sector of 360° · 25 : 100 = 90°. A diagram should have a title, axis names and units. Reading a diagram we can find the biggest and smallest value and the difference.
Worked examples
Favourite fruit: apple 9, pear 6, grape 12, plum 3. The tallest bar in a bar chart is grape (12). Total 9 + 6 + 12 + 3 = 30.
If 15 out of 30 votes are for grapes, its sector in a pie chart is half the circle: 180°.
Class activity
“Chart workshop”: groups collect data on favourite colour and draw a bar chart on squared paper. Another group draws three conclusions from the chart.
Practice
1
In a favourite-fruit poll apple got 9 votes, pear 6, grape 12 and plum 3. How many votes in all?
30
2
In a pie chart, what angle does a 25% sector have?
90
3
In a pie chart, how many degrees is a 50% sector?
180
4
Which diagram shows weekly temperature change best, and why?
A line graph: it shows how a value changes with time by joining points.