A dot plot puts a dot above a number line for each result. The number under a stack is the value; the number of dots is how many times it happened. The mode is the value with the tallest stack. 'More than 2' leaves out the dots above 2. The range is the largest value with a dot take away the smallest value with a dot. For the median, count the dots from the left to the middle one and read its value.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- dot plot
- a number line with a dot for each result
- mode
- the value that happens most often (the tallest stack)
- median
- the middle value when the results are in order
Worked examples
Stacks: 0 has 2 dots, 1 has 5, 2 has 3, 3 has 1. What is the mode?
- 1.The tallest stack has 5 dots.
- 2.It is above 1, so the mode is 1.
= 1
Same plot: how many results are more than 1?
- 1.More than 1 means 2 and 3.
- 2.3 + 1 = 4.
= 4
Same plot: what is the median?
- 1.There are 11 dots, so the median is the 6th dot.
- 2.Running totals 2, 7: the 6th dot is above 1.
= 1
For parents
Method: Each dot is one result
What to say: Is the answer a value along the line, or a number of dots?
Common mistakes:
- Gives the number-line label instead of the number of dots above it.
- Counts the stack next to the value asked about.
- Gives how many dots are in the tallest stack instead of the value under it.
- Gives the largest value as the mode.
- Counts the dots at x as well when asked for 'more than x'.
- Counts the dots below x instead of above it.
- Counts the stacks instead of the dots in them.
- Uses the ends of the number line instead of the smallest and largest data values.
- Gives the largest value as the range.
- Subtracts stack heights instead of values.
- Gives the position of the middle dot instead of its value.
- Takes the middle of the number line instead of the middle of the data.
- Gives the mode (tallest stack) as the median.