Frequency tables, diagrams, bar charts and histograms
Students may be familiar with drawing a range of charts, diagrams and graphs but may have less experience interpreting exactly what they mean. Use questions to challenge students understanding of the key features of a chart or graph. Ask students to state how the chart or graph supports their comments. Ask them to give examples of the most important features and maybe some less important ones that may not be immediately apparent.
The use of histograms is referred to under the section Health, disease and the development of medicines
Students are often confused about the difference between a histogram and a bar chart. This is can be reinforced by some text books and web links they see. A frequency diagram should only be referred to as a bar chart if it refers to discrete data.
Students often use graphs from packages like Excel without really thinking about whether they are suitable and often spreadsheet programs are rather cumbersome in creating suitable graphs for science lessons and contexts.
The need for these skills is most likely to occur in the Biology sections where it may well take the form or presenting and extracting data from in the Ecosystems topic as well as extracting data from graphs in the Coordination and Control topic.
Interpreting Data
A collection of resources, using science and other contexts to support students use of and understating of different graphs types.
Students can often draw bar charts etc. from given data, but find difficulty in interpreting them. This resource includes a unit on "Interpreting bar charts (using higher order questions)". Students look at the cards provided that show various data stories. The resources will help you prepare questions that relate to the charts so that learners can either hold up the chosen card and show you or give you an answer when you describe the chart. An example might be: Show me the chart that relates to recycling and shows that rates have increased year on year. This could be used as a starter to check student ability to interpret bar charts.
The structure of the resource could be used to present an alternative example related to the area you are teaching.
Representing Data
Produced by the Learning and Skills Improvement Service (LSIS) this resource includes a unit on Histograms (using co-operative small group work). This resources is aimed at mathematics practitioners but if you do need students to be able to work with unequal class sizes it could be used to check that they understand how frequency density is used when working with unequal class sizes. The strucutre of the lesson could alsobe adapted to the particular context you are working with.
Bar Charts
A simple introdcution to the characteristics and uses of bar charts. A bar chart is used to represent discrete data and should always be displayed with gaps between the bars.
Histograms/Grouped Frequency Diagrams
Histograms represent continuous rather than discrete categories. This means that in a histogram there are no gaps between the columns representing the different categories. The class intervals can be the same or different. This GCSE Bitsize link gives you an example using equal class sizes and avoids some of the confusion by describing the graph as a grouped frequency diagram.
Histograms - unequal class intervals.
Bear in mind that only students aiming for higher grades at GCSE will meet Histograms with unequal class intervals. This GCSE Bitesize link demonstrates how to construct a Histogram using unequal class intervals and frequency density.
