Mean, median and mode
Build a dot plot, find the tallest stack, the middle value and the balance point, and see which one an outlier pulls.
Standards: 6.SP.A.36.SP.B.5
1Wonder
Five friends read 2, 3, 3, 5 and 12 books over the summer. What is a “typical” number of books for this group? There are three different answers, and each one tells you something different.
2Explore
This activity needs a bigger screen
Turn your phone sideways, or open this lesson on a tablet or computer. The explanation and quiz below work here.
- Add a few dots. Where is the tallest stack? That is the mode.
- Watch the purple median line. Does it always land on a dot?
- Add one dot far away, at 10. Which moves more: the mean (the red pivot) or the median?
- Can you make a set of dots where the mean, the median and the mode are all the same?
3Explain
A set of data
Seven children told us how many pets they have: 2, 3, 3, 3, 4, 5 and 6. A dot plot puts one dot above each answer, so we can see the whole set at once.
Mode: the most common value. Median: the middle value when the data is in order. Mean: the total shared equally, sum ÷ count. It is the balance point of the data.
4Practice
What is the mode of 2, 3, 3, 5, 7?
5Recap
- Mode: the most common value (the tallest stack).
- Median: the middle value in order.
- Mean: sum ÷ count, the fair share and the balance point.
- An unusual value pulls the mean a lot but the median hardly at all.