Phenomenon
Life is diverse, yet there are some commonalities across organisms.
We can see patterns of "nested similarity" where some kinds of life are more similar than others. Among much of the diversity we see, there is a striking pattern where organisms are fairly well matched to their environments.
Question
What might we account for these patterns of Unity and Diversity? OR How can all organisms on Earth share so many characteristics and yet be so different? (Have YOUR students generate a question as a class about biodiversity that will focus their attention this year)
Model Ideas
This unit is meant to transition into the biology content for the year. No model at this time. Students may have some ideas that explain unity and diversity, but the curriculum doesn’t address model-building for these big questions until the end of the year (see Evolution on a Changing Earth).
Overview
Transition in from Oxygen. Now that we have an idea of how the Earth formed and came to resemble what we see today, we focus in on the specific subject of this biology class, living things!
We begin with an activity that exposes students to a number of diverse organisms: preserved, living specimens, photographs, or a combination. We conclude that Earth is home to an incredible array of vastly diverse species, each well-suited to its specific environment. We also note that though diverse, these organisms have many characteristics in common. Students generate a list that may include the following: are made of cells, have a life-span, reproduce, obtain food, produce waste, have DNA, sense and respond to their environment etc. This leads us to wonder how there came to be so many kinds of organisms that are so very different, but also have so many characteristics in common. This question frames the entire year and will be revisited throughout the year, but especially at the year’s end. Other important questions within this framework include: What are the commonalities that exist among all living things and what evidence supports this? Why do commonalities among all living things exist at all? Why are there so many species and how did they come to be? How does biodiversity among species change over time? What role does the environment play in shaping biodiversity?
Transition out to Natural Selection. Next we will explore biodiversity a bit further and specifically ask how populations change over time.
Advanced Planning
You will need to gather physical specimens or pictures for the Odd One Out activity.
1: Odd One Out Activity
Overview: Students explore the phenomenon of biodiversity on Earth by examining a number of organisms through the “Odd-One-Out” activity.
What we figured out...Our planet is full of wonderful, diverse organisms, and as different as they all are, they also have some similarities. In the next learning segment will discuss these similarities and differences.
2: Exploring Biodiversity
Overview: Students process the activity and describe unity and diversity patterns as a class.
What we figured out...Despite all the diversity of life on our planet there are several characteristics that every living organism has in common. We also figured out that the environment plays a role in how similar organisms can be very different.
3: Developing a Driving Question
Overview: Students generate the driving question about biology for the year.
What we figured out...We formed a question about life on this planet that will drive the year’s instruction. We wondered about the phenomena of life being so different yet having several similar characteristics, and we wondered about the role the environment plays in all this unity and diversity. We will work throughout the year to develop a series of models that will help us answer our overall question at the end of the year.