The three main parts of an ecosystem are = habitat, animals and plants.
An example of a sampling technique is -
a) dig a small hole to place a cup/jar into.
b) place the cup/jar into the hole with the top level with the ground so that animals can crawl easily in.
c) leave the cup/jar for some time.
d) come back and check the contents of the cup to identify and count the organisms that have been caught.
e) repeat to make results more reliable.
Possible sources of error are - (ways of lessening in blue!)
a) predators such as birds may see the trapped organisms and eat them. Place a leaf over the top to hide the cup/jar a little.
b) some of the organisms may eat each other or escape. Place a substance, such as…