Editing Biomagnification (section)

== Demonstration ==
;Preparation: Prepare the small cups for the demonstration: Fill two thirds of the small cups with 5 clear marbles. The last third should get four of the clear marbles, and one of the red marbles.
;Presentation:
# Split the students into three groups. The first group will have two thirds of the students, the second group will only have two or three students, and the remaining students will make the third group. This demonstration works best with a total number of students between 18 and 40, but can be adjusted appropriately for smaller (or bigger) groups.
# Give each student in the first group a small cup of marbles, and have them start to wander around in a large group. Give the second group the large cups, and give the third group the mid-size cups.
# Explain to the audience that the first group represents minnows, the third group represents average-size fish, such as carp, and the second group represents the big fish, such as pike. Some of the minnows have ingested toxins, represented by their red marbles, but they aren't noticeably affected by them. Ask all the minnows to hide their marbles by putting a hand over the top of their cup, so that nobody can see who has a colored marble.
# Have the carp group now come in and "eat" minnows by taking the minnow's cup of marbles and pouring them into their own cup. Each carp can only eat a max of three minnows. When a minnow is eaten, they give their cup back to the presenter and return to their seat. If a carp has two red marbles, then it cannot eat anymore because it is "sick". A carp cannot choose to not eat a minnow; They have to take the marbles of any minnows they get.
# Look at the carp cups. Do any of them have two red marbles? Now have the carp hide their marbles by putting a hand over the top of their cups.
# Now have the pike group come and "eat" the carp by taking the carp's cup of marbles and pouring them into their own cups. Each pike can only eat two or three of the carp, depending on the carp-to-pike ratio. If a Pike ends up with three or more red marbles, then they become "sick" and cannot eat anymore.
# Look at the pike cups. How many of them were sick? If any of them have more than three, then they "die" from the toxins. Did any die? Collect all materials from the students and have them return to their seats before giving the explanation.