• Assess student understanding of biological organization by providing feedback through the card sequencing activity.

• At the close of the discussion, check for understanding and correct misconceptions revealed by student responses, and collect exit tickets for individual assessment.

Give groups of students a different set of cards with pictures representing the levels of biological organization (S-B-3-3_Biological Organization Cards.doc). Have them put the cards in order of complexity. Discuss how they knew the order in which to put them. What is the pattern? Most will recognize that they were getting bigger; some will see that a simple system becomes part of the next level, which is part of the next level, etc. Explain that a classification system that is organized from greatest to least forms a hierarchy. For example, the king has the most power, but there is only one. His advisors have less power, but there are a few more of them, and so on.

Activity: Pyramid Foldable

Students will make a pyramid foldable to reinforce the hierarchical nature of the biological levels using a Pyramid Foldable (S-B-3-3_Pyramid Foldable.doc). Demonstrate how to cut the foldable to make a pyramid. Have students save the strip of paper that they cut off as their exit ticket. Before students tape the pyramid together, guide them in writing the levels of biological organization on one side, with the smallest at the top. On the next side, have students write the description for the corresponding level. Have students write their own definitions/descriptions for the different levels from looking at the pictures. On the last side, students will list examples of the levels. See the chart below.

Side 1	Side 2	Side 3
Molecules	Different atoms bonded together	DNA, protein, lipids, carbohydrates, water, salt, CO2, glucose
Cells	The smallest unit that is capable of carrying out all the life processes	Prokaryotes, white blood cells, epithelial cells, bacteria, yeast
Tissues	A group of cells, not necessarily of the same kind, that work together to perform a specific task	epithelial, connective, nervous, muscle
Organs	A group of different tissues that form a singular unit and perform a similar function	Heart, brain, kidney, skin
Organ systems	A group of organs that interact to perform a similar function, i.e., circulatory system, excretory system	Circulatory system, digestive system, excretory system, nervous system, respiratory system
Organism	An individual living thing, can be unicellular or multicellular	Humans, bird, earthworm, plant, bacteria, yeast
Population	Members of the same species that inhabit the same area	White-tailed deer in PA, Red Maples in Allegheny National Forrest
Community	All the different populations that inhabit and interact in a specific area	Pond, grassland, deep ocean
Ecosystem	All the biotic and abiotic factors that inhabit and interact in a particular area	deciduous forest, coniferous forest, grassland, desert, marine, freshwater
Biosphere	All the different ecosystems that make up the planet; Earth	Earth, where life exists

Students may want to tape the table into their notebook and not tape the sides.

First, explain that not all levels of organization exist among all organisms. Prokaryotes are single-celled organisms. They do not have tissues, organs, or organ systems. There are also single-celled eukaryotes (e.g., euglena, yeast, amoeba, diatoms). Though some organisms lack more complex structures like tissues, organs, and organ systems within themselves, they can make up even larger systems like populations, communities, ecosystems, and the biosphere.

Explain to students that as we ascend up the pyramid into more complex systems, properties that did not exist before will emerge. These are called emergent properties and the properties can be surprising. For instance, if you look at a DNA molecule or an enzyme, could you tell that it might form a living cell? When different cells grow together to form a tissue, the cells can communicate with each other via chemical messages. Examples of organs interacting with tissues and other organ systems are the heartbeat and breathing rates increasing in response to lower O₂ levels in the blood. Another example of an emergent property is humans forming complex societies made up of populations.

To close this lesson, ask students “Where on the pyramid do the properties of life emerge?” (cells) “Do all organisms have organs?” (No, prokaryotes are unicellular. Protists and plankton are also unicellular). “At which level do we begin to consider abiotic factors?” (the ecosystem level) Have students give examples of each level or give an example and students choose the correct biological level. “A kidney is an example of ____?” (an organ) On the Pyramid Foldable exit ticket, have students write an example of a biological level and which level it represents.

Extension:

• Students who may be going beyond the standards can research the emergent properties that occur in an organ system. Have students make a poster that presents a feedback loop that occurs in that system.

• For extra practice with the standards, students can play a card game with the biological level cards that they used in the introduction. The game should include sequencing or describing the levels of biological organization (e.g., Go Fish or Solitaire). For extra practice with the standards, have students compare and contrast the level of classification of protists, bacteria, and red blood cells.