1718 WB1Z CH3 Lesson 3

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 1

Which exercises should I discuss on the board?

How to plot a graph from a table

Coordinate systems are drawn using a pencil and geotriangle.
Graphs are plotted (= drawn) using a pencil and sometimes a geotriangle.

How to plot a graph from a table

1. Draw a vertical axis using the information in the bottom row. Look at the highest and lowest value and decide which steps to use* and if you need to use a zigzag.

*An axis should be between 5 and 15 cm long. A good way to decide what steps to use is to look at the difference between the highest and lowest value and divide this by 10. Then round off to a whole number. Good steps are 1, 2, 5, 10, and multiples of 10.

Bottom row ranges from 5 to 220
(220 - 5) : 10 = 21.5, so use steps of 20 on the vertical axis.
A zigzag is not needed, because the lowest value is almost 0.

How to plot a graph from a table

2. Draw a horizontal axis using the information in the top row. Look at the highest and lowest value and decide which steps to use* and if you need to use a zigzag.

*An axis should be between 5 and 15 cm long. A good way to decide what steps to use is to look at the difference between the highest and lowest value and divide this by 10. Then round off to a whole number. Good steps are 1, 2, 5, 10, and multiples of 10.

Top row ranges from 0 to 60
60 : 10 = 6, so use steps of 5 on the horizontal axis.
A zigzag is not needed, because the lowest value is 0.

How to plot a graph from a table

3. Label the axes. This means you write down at each axis what the variable for that axis is and what unit it is measured in.

Top row says "time in seconds", so this is written at the horizontal axis.
Bottom row says "speed in miles per hour", so this is written at the vertical axis.

How to plot a graph from a table

4. Plot the points from the table and join them.
If a value is not on one of the lines of the grid paper, measure where you should plot the point.
If the graph is a straight line, use a geotriangle. If the graph is not a straight line, connect the points with a smooth line.

One grid square (1 cm) is 20 miles on the vertical axis, so 10 miles is
5 mm and 5 miles is 2.5 mm.

The graph is not a straight line, so draw a smooth line. You do not use a geotriangle.

Homework Friday

Make and correct: 17, 19, 20, 22, 23, 24, 25