Teaching sequence

Work through this resource material in the following sequence:

5 minutes – The story so far...
5 minutes – Tune in: What does natural selection look like?
20 minutes – Find out: How life began and changed
25 minutes – Take action: Beak evolution experiment
5 minutes – Reflection

Presentation slides

We strongly encourage you to use the Presentation Slides as a guide for yourself and your students through this lesson.

The story so far...

Step 1.

Revisit the story so far, using the Threshold Cards as a guide to retell the story of the history of the universe. Students should be involved in the retelling - you might nominate different students each lesson to be responsible for a different threshold. Prompt them to explain what ingredients were present in the universe at the time, what goldilocks conditions existed to enable a change, and the new complexity it resulted in.

Remember, students' explanations can't be wrong, but you might supplement them with the information below.

In the beginning, we weren't sure there was anything in the universe. If there was, we don't know what it was. We also don't know what the conditions were like. However, something happened, which we know as the Big Bang. This caused the universe to change so much that we recognise it as a new complexity - almost a totally new place. After that, we had space, time, matter (hydrogen and helium), and energy (gravity and electromagnetism).
These were perfect Goldilocks Conditions for something to happen. First, gravity pulled matter together. Inside these fusions, it was more than 10 million degrees Celsius. Suddenly, stars lit up. Galaxies, clusters, and superclusters were formed.
The stars started to age and die. They were running out of hydrogen and helium. Giant stars collapsed, fusing to create more complex elements in the billion-degree temperatures. After a time, 92 elements were present in the universe, making our universe a far more complex place.
Now gravity started to have an impact on these new elements. They underwent accretion. Random collisions started to happen, where elements gathered together and combined. Eventually, these clusters grew big enough to create comets, asteroids, and - most exciting of all - planets. Much more complex structures, including our Solar System, developed in the universe.

The universe had changed once again.

Tune in: How does natural selection work?

Step 1.

Ask students what they know about natural selection.

Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as the main process that brings about evolution.

Step 2.

Can students come up with any examples of natural selection? Students might be aware of an animal that is better adapted for their environments, such as a bird growing a specific beak to be able to feed better, or an animal with great camouflage enabling it to survive predators much better.

We're going to have a look at this second one in more detail.

Step 3.

On their independent devices, direct students to the Peppered Moth simulation game.

In this game, students play as a bird trying to eat moths. Students are welcome to choose to play in either the 'light' forest with white-barked trees, or the 'dark' forest with dark-barked trees.

Allow students to play and see what they discover. The game has a natural time limit and some useful graphs are produced after the time is up.

Step 4.

After students have played a few rounds, ask them to keep their results.

What did students discover?

The game starts with an even 50/50 split of dark and light moths in the environment. However, the catch is that one population of moths is dramatically reduced by being eaten by the bird.

Can students figure out why?

Students should be able to explain that one type of moth will be more difficult to see as it camouflages against the tree bark (depending on the forest).

Step 5.

This is a very simple example of natural selection. Being a certain colour means you're less likely to be eaten by a bird, and therefore more likely to have babies.

This is how a certain colour of moth becomes more and more dominant.

Provisions for Learning Extension: Independently, students could investigate more about natural selections through the example of Peppered Moths (https://askabiologist.asu.edu/peppered-moths-game/natural-selection.html)
If you would like more background information for yourself, go to Peppered Moth and Natural Selection (butterfly-conservation.org/moths/why-moths-matter/amazing-moths/peppered-moth-and-natural-selection).

We'll come back to moths, natural selection, and evolution after we've had a closer look at how life developed on Earth in the first place.

Find out: How life began and changed

You can also use the Presentation Slides to guide you through these steps.

Step 1.

Watch:

A Big History of Everything | Unit 5 (https://youtu.be/6dDSqg_fK5o?feature=shared)

Step 2.

Watch:

What do Biologists do? (https://www.youtube.com/watch?v=g45sc3tggv0)

Step 3.

Discuss any new vocabulary and the meaning of any unknown words that came up in these videos.

If you are keeping a word wall across the course of this unit, update it with new terms and definitions.

Step 4.

The key ideas:

The two views on how life began on Earth
- via meteors or
- chemical reactions near undersea volcanoes.
Bacteria was the first and simplest form of life

Step 5.

Watch:

From the Big Bang to Me (https://www.youtube.com/watch?v=nYkdDniQJyw)

Step 6.

Can students provide their own definition of DNA and evolution?

Students love to know that DNA has a very long name: deoxyribonucleic acid. That's a real mouthful. Luckily, you can call it DNA for short.

Explain that DNA is found in all living things, including YOU! DNA is in every cell of your body and is shaped like a long, twisted ladder. The steps of this "ladder" are made of only four building blocks, called bases. These bases are known by the letters A, C, G, and T.

Step 7.

Discuss the image of the range of birds. Prompt their thinking by asking:

What do you notice about these birds? What is the difference between them? Their beaks are all of different lengths and shapes.
Are they the same bird? You might think they're all different, but all of these birds are finches.
So why do they look different? This is the key question. Come up with some hypotheses of why the same bird might have different beaks. Hint: It has something to do with survival, evolution and natural selection.

Instead of just giving you the answer, we're going to do an experiment to find out.

Take action: Beak evolution experiment

Step 1.

Set up six distinct stations around the classroom. You might need to rearrange some tables.

Place each collection of 'food' (marbles, pipe cleaners, toothpicks, paper clips, beans, and paper squares) on their own station.

Each station should also contain one of each type of 'beak': one pair of scissors, one pair of tweezers, one teaspoon, one clothes peg, one fork, and one knife.

Step 2.

Split students into groups of six. If there are more than six students in a group, that's fine, the group will just have to share in the experimenting.

Step 3.

Explain to students that they are going to rotate around each station.

The goal of the experiment is to find which 'beak' is best at picking up which 'food' by measuring how many of each type of food each beak can pick up in one minute.

Step 4.

Before we begin, let's make some hypotheses.

Take students to the first station with the marbles. Show them the six different implements on the table. Which 'beak' do students think will be best for picking up the marbles: the scissors, the tweezers, the teaspoon, the clothes peg, the fork, or the knife?

Direct students to write their hypotheses in the space indicated in the record table on the Student Worksheet.

Step 5.

Repeat this at all of the remaining stations.

Step 6.

Now assign one group of students to each of the six stations. Each student in each group picks a unique 'beak', which they can select now.

Step 7.

Instruct students to spread the cup of 'food' across their table. Be careful with the marbles - they're likely to roll away!

Step 8.

Put 60 seconds on the clock. When the timer starts, students have to pick up as many pieces of 'food' as they can and return it to the cup. Students should keep track of how many they're able to pick up within the minute.

Stop when the timer hits zero.

Step 9.

In the spaces provided, students record how many pieces of food they were able to pick up with their beak.

For example, a student at the marbles station may have been able to pick up three marbles using the scissors. Someone else in their group may have been able to pick up ten marbles using the fork. A student in another group may also have used the fork, but was collecting toothpicks instead.

It's important to fill in the right section for both the 'beak' and the 'food' type students were using.

Step 10.

Students fill in the rest of their table using the results from the other members of the group.

Step 11.

Groups rotate around the other stations of food. They might like to swap 'beaks', or they might stick with the same instrument.

Step 12.

Once all groups have tried picking up all types of food, they can analyse their results. Fill in the final column of the table about which beak was 'best' for each type of food, based on which beak picked up the most pieces.

Reflection

Compare your results as a class. Prompt discussion by asking:

Were results consistent across the whole class? That is, did everyone choose the same beak as best for the same type of food? Or do some groups disagree on the best beak? This is quite an important scientific question, especially in our role as claims testers. Results should be the same across the whole class, but there are a number of reasons why they might not be. It could be that Jason has pretty shaky hands and wasn't able to pick up any piece of food with the scissors, even when it was the best break for the job.
Were there any beaks that were able to pick up more than one food well? Can you explain why?
Which beaks collected the least amount of food? Can you explain why? Some beaks are just a bit more generalised, making them kind of good at everything. Some beaks are highly specialised, making them extremely good at one thing in particular, and not much good at much else.
Which beak would you prefer to evolve? Why? Guide students towards an understanding of this experiment demonstrating natural selection and evolution. A useful beak is able to eat different types of food, which means it can eat more food, which means it will survive by not going hungry, which means it is likely to have babies with even more of the same beak. Bad beak = no food = not surviving.
What has this got to do with finches? Darwin saw exactly the same experiment playing out in real life. He saw many different finches each with a beak specialised at being great for picking up a certain type of food found in their natural habitat, increasing their chances of survival.

After the discussion, students can answer these questions on the Student Worksheet.

Threshold crossed

Finally, tell the next part of the history of the universe that we have just covered.

"Now there was just the right amount of energy for many different chemical reactions to take place. And, importantly, there was liquid water, which made it easier for matter to combine and recombine.

So that's exactly what it did!

Complex chemicals, including DNA, came together to form new life that could maintain and refuel (feed) itself, adapt to changes around it over time, and copy itself (reproduce).

The universe had changed once again."

Stick your Threshold 5 Card up around the classroom somewhere as an indicator of a threshold being crossed!

Students fill in their Threshold Reflection Sheet.

Where to next?

Students' learning throughout Big History is leading them towards designing future cities. As Big Historians, we are travelling through 13.82 billion years of our universe’s history to find solutions to the United Nations' Sustainable Development Goal #11: to make cities inclusive, safe and resilient.

Remind students that the Sustainable Development Goals are the world’s to-do list for people and the planet. We all need to be a part of the process. 193 nations came together and agreed on one common list for all of us that helps make the planet and our communities stronger.

What will be our first touchdown threshold in our next lesson? Early Humans: What makes humans different from other species?

Big History Passport check-in

After this lesson, students should have added to their Big History Passport:

Student Worksheet - Beak experiment
Threshold 5 Reflection Page

Differentiated learning

Extension -

Make your own peppered moths (www.youtube.com/watch?v=hywyokre_vw)
You may like to locate the book Moth in your library and read it to the class. Or you can watch the author read it: Great Science Share for Schools, Listen as Isabel Thomas shares her story Moth (www.youtube.com/watch?v=Dac7uDkzxg). Note the author is also a scientist so you can point out she is an authority for ‘evidence’. ( Ref: Isabel Thomas (Author), Daniel Egnéus (Illustrator), Moth: An Evolution Story, Bloomsbury children’s books, 2020)
Interactive microscope: looking at insects through a microscope

Big History - Life on Earth

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