Uploaded August 2023 | Updated September 2026, 4 hours ago

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You can find all my A Level Biology videos fully indexed at freesciencelessons.co.uk/a-level-revision-videos/a-level-biology

In this video, we look at random and non-random sampling. First we explore how we can use random numbers to carry out random sampling and the benefits of doing this. We then look at non-random sampling including opportunistic sampling, stratified sampling and systematic sampling (line transect and belt transect).

Woodland Stream
commons.wikimedia.org/wiki/File:Woodland_stream_-_geograph.org.uk_-_4508346.jpg
Woodland stream by Phil Platt, CC BY-SA 2.0 creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons

Sampling
commons.wikimedia.org/wiki/File:Plant_study_-_quadrats_and_line_transects_(6987006283).jpg
U.S. Fish and Wildlife Service Headquarters, Public domain, via Wikimedia Commons

Sampling 2
commons.wikimedia.org/wiki/File:08Biocrust_(6517406791).jpg
SonoranDesertNPS from Tucson, Arizona, CC BY 2.0 creativecommons.org/licenses/by/2.0, via Wikimedia Commons

Pond edge
commons.wikimedia.org/wiki/File:Pond_edge.jpg
MargaritaRouki, CC BY-SA 4.0 creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Arctic Char
commons.wikimedia.org/wiki/File:Man_holding_arctic_char.jpg
Klaus Jost, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Transect
commons.wikimedia.org/wiki/File:Practice_Transect_(36453810981).jpg
Shenandoah National Park from Virginia, Public domain, via Wikimedia Commons

Transect 2
commons.wikimedia.org/wiki/File:Intertidal_transect_quadrat_sampling.jpg
ThalassaLib, CC0, via Wikimedia Commons