Skip to content

Data and probability, grade 8

Eighth-grade data and probability.Subjects

The topics, in order:

  • collecting data, frequency and relative frequency, charts;
  • the measures of centre: the mode, the mean and the median; the range;
  • comparing two sources of data;
  • interpolation and extrapolation: estimating between the data and beyond it;
  • probability.

There are two kinds of lessons:

  • Learning lessons – an explanation, solved examples and a few questions to try;
  • Practice lessons – questions only.

How the page works: Using a page.

  1. Collecting dataLearningA question, a survey, a population and a sample; categorical and numerical data; from raw data to a frequency table.
  2. Frequency and chartsLearningFrom a frequency table to a bar chart, a line chart for a quantity that changes over time, and reading a chart: the most frequent, the total, how many more.
  3. Relative frequencyLearningThe relative frequency – a frequency divided by the total – as a fraction, a decimal and a percent; they add up to 1; comparing groups of different sizes; and from a relative frequency back to a frequency.
  4. Practice: data and frequencyPracticeKinds of data, population and sample, the frequency table, reading and drawing charts, and relative frequency.
  5. The mode and the rangeLearningThe mode – the value that comes up most often, also in categorical data; two modes or none; the range – how spread out the data are; from raw data, from a frequency table and from a chart.
  6. The meanLearningThe mean – the sum divided by the number of data; the mean as sharing equally; the mean from a frequency table; a missing value from the mean, by an equation; what adding a value does to the mean.
  7. The medianLearningThe median – the middle value of a sorted list; with an even number of data – the mean of the two middle ones; the median from a frequency table; an outlier pulls the mean, not the median; choosing a measure of centre.
  8. Comparing two sources of dataLearningComparing two groups or two sources of data: by the mean and the median, and by the range; two series on one chart; drawing a conclusion from data, and when the data are not enough for one.
  9. Interpolation and extrapolationLearningData over time on a line chart: interpolation – estimating between two data points; extrapolation – estimating beyond the data, and why it is less reliable; a straight-line trend and its formula, y=mx+b.
  10. Practice: measures of centre, comparing and estimatingPracticeThe mode, the mean, the median and the range, from raw data, a table and a chart; a missing value from the mean; an outlier; comparing two sources; interpolation and extrapolation.
  11. ProbabilityLearningExperiments and outcomes, events, equally likely outcomes, the probability of an event – from 0 (an impossible event) to 1 (a certain event) – and comparing chances.
  12. The complement and relative frequencyLearningThe complement of an event, a probability as a fraction, a decimal and a percentage, the relative frequency coming near the probability when an experiment is repeated many times, estimating a probability from data, and the expected number of times.
  13. Practice: probabilityPracticeThe probability of an event, certain and impossible events, comparing chances, the complement, estimating a probability from data and the expected number of times.
  14. Review: the whole coursePracticeQuestions on every topic: data, tables and charts, relative frequency, the mean, the median, the mode and the range, comparing two groups, estimating between the data and beyond it, and probability.
Last updated on