Grade 7: Statistics

Warm up with a few quick statistics warm-ups on the board while the class settles, so every child starts thinking about the skill.

Mean, median, mode and range are four different ways to summarise a numerical data set: the mean is the equal-share average, the median is the sorted middle, the mode is the most frequent value, and the range is the spread from lowest to highest. Model the method clearly, thinking aloud:

• Start with the mean as 'sharing the total equally': add every value, divide by the count.
• Teach the median as 'the sorted middle': sort the data first, then find the middle value (or average the two middle values for an even count).
• Introduce the mode as simply the most frequent value, and show it can be none, one, or several.
• Teach the range as highest minus lowest, a measure of spread rather than a typical value.
• Finish by comparing all four on one data set with an outlier, so students see why the 'right' average depends on the question.

Work this through step by step on the board, then have the class talk you through a second one.

• Data set: 2, 4, 4, 6, 9
• Mean: (2+4+4+6+9) / 5 = 25 / 5 = 5
• Median: sorted is 2, 4, 4, 6, 9, the middle (3rd) value is 4
• Mode: 4 appears twice, more than any other value
• Range: 9 - 2 = 7

Do the first few questions of the practice worksheet together, one child explaining each step. Check for understanding before releasing the class to work alone.

Students complete the practice worksheet independently while you circulate and support.

Circulate and look for these, they are the usual sticking points:

• Assuming 'average' always means the mean, when it could mean any of the three.
• Finding the median without sorting the data first.
• Assuming every data set has exactly one mode.
• Confusing the range (a single number, the spread) with the number of values in the set.

Pull the class back together. Ask one child to explain statistics in their own words, pose a single check question everyone answers on a mini whiteboard, and name what you will build on next lesson.

Use the independent worksheet as the evidence. A child who can complete it accurately and explain one answer has met the objective; anyone who cannot needs the easier level and a short reteach next session.