topic: Cells
activity: Building blocks of life
In this activity, students learn that the cell is the fundamental unit of life and also become familiar with the
cell hierarchy.
Suggested time: 45 minutes
Summary of Key Learning Points
Students:
- discover that the cell is the basic unit of life
- recognise that organisms can be unicellular or multicellular
- identify the three tenets of modern cell theory
- understand the cell hierarchy from cell to organism
Building blocks of life
15 minutes
On the first page students choose what building blocks humans are made of. Some students might argue
that atoms is the correct answer. Discuss the difference between the basic unit of life and the basic unit of
matter.
Answer: Cells (Inquiry point 1)
Next they must think about whether or not we have different cells in our bodies. Brainstorm with the students
to see how many different types of cells they can name.
Answer: There are different types of cells (Inquiry point 2)
After this, they are asked if they think plants and animals are made of cells.
Answer: Yes (Inquiry point 3)
Define the terms 'unicellular' and 'multicellular'. Give examples of each. There are four organisms on this
page. Emphasise to students the simpler structure of single-celled organisms, whereas multicellular
organisms have more complex structures like legs and organs.
Answer: Amoeba, Foraminifera, Bacteria (Inquiry point 4)
Talking point: How do unicellular organisms satisfy the seven characteristics of living things, for example,
how does an amoeba excrete wastes?
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topic: Cells
activity: Building blocks of life
The Science extra shows the relative sizes of some common cells and microbes, as well as a water
molecule. Make sure students understand what a nanometre and micrometre are.
How do we know about cells?
10 minutes
Cell theory has been developed over many years. This is a good place to talk to students about how ideas
change over time as new evidence comes to light. This page talks about the idea of spontaneous
generation, which was popular in medieval days. Read and discuss all three tenets of modern cell theory.
Answer: All cells come from pre-existing cells (dismisses the idea of spontaneous generation). (Inquiry point
5)
Class activity: Get students to research one of the people who contributed to cell theory. Choose from:
Janssen, Hooke, Redi, Leeuwenhoek, Dutrochet, Brown, Schleiden, Schwann, Virchow.
From cells to tissues, tissues to organs, organs to organ systems
15 minutes
The cell hierarchy is:
Cell to Tissue to Organ to Organ system to Organism
This is explored piece by piece with a focus on the circulatory system. Note that 'body system' is the same
as 'organ system'. The page with three slides shows different types of tissue found in the heart.
Answer (correct slide order): (Inquiry point 6)
On the next page students select the brain, heart and kidneys and identify their functions.
Answers:
Brain: Centre of nervous system
Heart: Pumps blood
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topic: Cells
activity: Building blocks of life
Kidneys: Filter blood (Inquiry point 7)
The next page talks about the arrangement of organs in organ systems and organ systems in organisms.
Read through the information with the students and make sure they understand.
Cell hierarchy
5 minutes
The final page allows students to construct their own cell hierarchy.
Answer (left to right): Cell (cardiac cell) to Tissue (cardiac tissue) to Organ (heart) to Organ system
(cardiovascular system) to Organism (human) (Inquiry point 8)
Suggested completion levels
Basic - Inquiry point goal = 4
Students at this level will: recognise the difference between a unicellular and a multicellular organism; state
that the cell is the basic unit of life; identify at least three different parts of cell hierarchy.
Core - Inquiry point goal = 6
Students at this level will: explain the difference between a unicellular and a multicellular organism; state that
the cell is the basic unit of life; recall the three tenets of cell theory; identify the correct order for the cell
hierarchy.
Advanced - Inquiry point goal = 8
Students at this level will: explain, with examples, the difference between a unicellular and a multicellular
organism; state that the cell is the basic unit of life; recall the three tenets of cell theory; identify the correct
order for the cell hierarchy and give examples for two different body systems; be able to estimate the size of
common cells.
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