Teacher Resource 1 –
Demonstrating the value of quadrats and
sampling
The great value of this activity is that any area of grassland with at least 10 different plant groups
(recording all mosses as just moss and all grasses as grass) that is at least 10 m by 10 m in area can
be used for this practical activity. This should mean that playing fields or other areas of grass close to
school buildings are suitable.
Beforehand, it is good to explore the area and collect representative samples of each plant type
(preferably at least a leaf and flower), identify them and then arrange as labelled specimens on a piece
of A4 paper. A little judicious sellotape then allows the page to be photocopied which creates a very
workable pictorial key.
Armed with the key, students (in small groups) walk around the area to be surveyed and identify the
plants they can and for each type give an indication of abundance using an ACFOR scale. Being
subjective, you can leave students to decide what equates to Abundant, Common etc. but don’t give
them long to do this. This ensures that they don’t copy each other and that at least one or two plants
get missed. These values could be transferred to a pre-prepared results table. Any plant that is on the
list but wasn’t seen gets an N for absent.
Next, remind the students of the principles of using a quadrat and random sampling to obtain a
representative sample of the environment and then armed with their key, recording sheet and random
numbers, each group starts to record the percentage cover of each plant type they find in several
different quadrats. Ideally it would be good to have the class as a whole collect 30+ quadrats worth of
data, but anything more than 15 quadrats of carefully collected data will show the idea. Results sheets
are kept safe for next time (after students have recorded their names at the top). Ten students now
have the task of working out the mean percentage cover for their chosen plant (from all the individual
sheets) before next lesson.
Back in the class each student now has a blank recording sheet to make a neat copy of their own
group’s data. Importantly they now also have a final column for mean percentage cover. A little data
analysis is now required to rank all the ACFOR values collected first (with any ‘N’ value having the
lowest rank) and then all the mean percentage cover values. Each plant now has a pair of coordinates
provided by its subjective ACFOR rank and mean percentage cover rank, which can then be plotted on
a scattergram. Plotting the 10 or more values doesn’t take long and provides a nice basis for
discussion.
Version 1
Ecosystems 6.3.1
1
© OCR 2016
Version 1
Ecosystems 6.3.1
2
© OCR 2016