Part of:
Convex Seascape SurveyThis lesson helps students understand that oceans can change over time and how these changes affect marine life. Students will explore both natural cycles and human-caused changes, with a focus on temperature impacts on marine habitats and animals through visual media and movement-based activities.
Notice that oceans change in different ways
Understand that some changes happen again and again (like tides)
See that other changes happen because of people
Discover how ocean animals find homes and food when things change
1. Natural changes (12 mins)
Begin the lesson by connecting to changes that students can observe in their daily lives:
Who can tell me something that changes around us?
Maybe something that looks different today than it did yesterday or last week?"
Show slide 4 with examples of natural changes that students would recognise. Ask students to observe differences in the sets of pictures between winter and summer and day and night. See if any students can give reasons for the changes.
Click on the video link on slide 5 to play a video showing a series of time-lapse sequences. The first sequence shows how a tree changes through the year. Encourage students to notice how the leaves bud, grow, change colour, and fall as the seasons progress. Emphasise that this is a natural cycle, with autumn leading into winter and then spring again. The second sequence shows a city change throughout a night and day. Then, the final sequence shows how water moves in and out at a beach over a day. Point out how the tide goes in and out twice every day. The water comes in (high tide) and goes out (low tide).
Share that these changes happen naturally and in cycles: they happen over and over again. The tree changes with the seasons every year. The tide goes in and out every day. The ocean has many natural cycles too, like waves and tides that follow patterns we can predict.
Discussion points to explore with students:
Have you ever visited the beach twice in one day and noticed the water was in a different place?
What other things in nature change in cycles or patterns? (Examples might include: moon phases, day and night, weather patterns)
How do these changes affect what people do? (Such as wearing different clothes in different seasons, sleeping at night vs. playing in daytime)
Optional active learning
Conclude this section with a quick "freeze frame" game. Share with students that they are going to use body movement to examine some of the changes. When you say “freeze” they have to stand as still as statues.
Guide students through scenarios such as:
Show me how a tree looks in summer with full leaves (students stretch arms up high)
Now show me how the same tree looks in winter" (students drop arms down)
Show me how water moves when the tide is coming in" (students move forward with the waves)
Now show me the tide going out" (students move backward)
2. Human-caused changes (12 mins)
This step changes the discussion from the cycles of natural changes to changes that people can cause. Show the slide summarising two examples of human-caused changes from 1984 to 2020. Using slide 9, point to the images of Dubai's transformation from a small coastal town to a sprawling mega-city with artificial islands and skyscrapers. Then direct attention to the satellite images showing Greenland's sea ice loss over the same period. Emphasise the big changes that they can observe. These changes are different from the natural cycles because of what people have built or how they have changed Earth’s temperature.
Show the Google Earth animations of environmental changes from 1984 to 2020 on slides 8 to 10, providing brief background information for each:
Nuflo De Chavez, Bolivia: students may spot how the area went from a thick forest full of nature to an area with farms and roads.
Dubai, UAE: students may spot how Dubai started quite small before developing into a huge city, even with islands built in the shape of palm trees and a map of the world.
Mylius-Ericksen Land, Greenland: students may notice the sea ice loss in this area of northern Greenland as well as the retreat of glaciers.
Emphasise that these changes are different from tides or seasons. They don't naturally go back and forth in a pattern. Once forests are cut down or ice melts, they don't automatically grow back or freeze again quickly. These changes are happening because of things people do and choices people make.
Optional active learning
Facilitate a think-pair-share activity to deepen understanding. Ask students to think individually for 30 seconds about:
What do you notice about these changes?
Are they fast or slow?
Do they go back and forth like tides?
Have students turn to a partner and share their thoughts for 1-2 minutes. Bring the class back together and invite several pairs to share their observations.
Discussion points to guide the conversation:
Did these changes happen quickly or slowly?
Do you think the forest will grow back on its own soon? Why or why not?
What might happen to animals that lived in these places?
How are these changes different from the tide going in and out?
3. Ocean warming (8 mins)
Display the prompt slide 14 and pause briefly to let students consider this statement. Explain that we have seen how forests can change and cities can grow. Now we're going to look at something harder to see: how the temperature of our oceans is changing.
Show the NASA animation depicting ocean temperature changes from 1880 to the 2020s on slide 13. Before pressing play, explain to students how to interpret what they'll be seeing:
This special map shows how warm or cool the ocean water is all around the world.
Blue colours show that the water is cooler.
Red and orange colors show that the water is warmer.
Watch carefully how the colors change from long ago until today.
Play the animation through once, allowing students to observe silently. Then, play it again, asking students to make you pause the video as they see changes happening.
Lead a guided discussion:
What colours did you see the most at the beginning of the video? What about at the end?"
What does it mean when we see more red areas on the map?
Did the ocean temperature change a little bit or a lot over time?
Where do you see the most warming happening?
Connect back to previous learning. Remember the ice we saw melting in Greenland? Now we can understand why that's happening. The ocean water around it is getting warmer, which makes the ice melt faster.
Explain the significance of this warming and its effect on animals that live in the seas.
To conclude this section, summarise that the ocean is getting warmer because of changes people have made to our planet. This warming doesn't go back and forth like the tides. It is continuing to get warmer. Next, we'll learn how these warming oceans affect the animals.
4. Effects on ocean animals (8 mins)
Begin this section by displaying the global map showing ocean temperature changes. Share with students that they have learned that our oceans are getting warmer. The map on slide 15 shows how much warmer the ocean is now compared to the past. The red and orange areas show where the ocean has warmed the most. Take a moment to point out areas with significant warming, particularly in the Arctic and coral reef regions.
Move onto the spot the difference activities, explaining how this warming is affecting real places in our ocean and the animals that live there.
Introduce the spot the difference activity and distribute mini whiteboards, markers, and erasers to each pair of students.
First, display the Bering Sea comparison images on slide 16 showing sea ice loss between April 2014 and April 2019. Ask students to write or draw at least two changes on their whiteboard.
Allow pairs 2-3 minutes to examine the images and record their observations. Walk around the room to support students who might be struggling, offering prompts.
Invite students to share their findings with the class. Record their observations using their own words where possible, but help them use vocabulary such as "less," "melting," "smaller," "disappearing," etc.
Next, repeat this for the coral reef on slide 17, comparing the progression from healthy coral (September 2015) to bleaching (February 2015) to dead coral (August 2015) in American Samoa. As background, explain that:
These pictures show the same coral reef in the Pacific Ocean but taken at different times during one year.
Coral reefs are special underwater habitats where many fish and sea creatures live.
Again, allow pairs 2-3 minutes to examine the images and record their observations before proceeding to share to the whole class. Record their observations, helping them use vocabulary such as "colour," "white," "brown," "healthy," etc.
Guide students to make connections between these changes and ocean warming: "Let's look at our two lists. What similar things are happening in both places? Both the sea ice and the coral reef are changing because the ocean is getting warmer. When the ocean gets too warm, ice melts and coral loses its color and can die."
To reinforce understanding, ask questions such as:
What happens to ice when it gets warm?
What happened to the coral's colours when the water got too warm?
Do you think these changes happened quickly or slowly?
What might happen to animals that need ice to live or fish that need coral for their home?
5. Ocean animal activity (15 mins)
At this point in the lesson, choose ONE of the following activities based on your class's interests, available space, and connection to previous learning. Both activities help students physically experience the challenges marine animals face due to habitat changes.
If you have time, you can, of course, choose to do both!
Activity option A: "Finding lunch on ice"
This activity simulates how polar bears depend on sea ice for hunting and how melting ice affects their ability to find food. Students will experience firsthand how habitat loss impacts predator success.
Activity Option B: "Stay safe on the reef"
This activity demonstrates how coral bleaching affects reef fish that depend on healthy coral for protection from predators. Students will physically experience the vulnerability created by habitat degradation.
Whichever activity you choose, be sure to allow time for a brief discussion afterwards about how students felt as their habitat changed. Connect their experience back to real animals facing these challenges in warming oceans.
6. Summary (5 mins)
Gather all students together in a circle to review the learning using the prompts on slide 22.
As part of the strategy to embed climate and sustainability learning throughout primary school, this lesson has been designed to develop pro-environmental values and build the foundational knowledge needed to address climate and conservation topics more fully in later years.
Values integration
Climate change links
This lesson helps students understand that while oceans naturally change, some new changes are affecting ocean life in concerning ways. By connecting local changes to more dramatic changes in coral reefs, students begin to grasp how warming seas affect ocean creatures and their homes. This creates a foundation for understanding climate impacts across different scales - from local beaches to global oceans - preparing them for learning about positive actions in the next lesson.
Change words: different, before, after, more, less.
Time words: today, yesterday, tomorrow, season, summer, winter.
Ocean words: tide, wave, storm, beach, sea.
Movement words: move, swim, rest, find, travel.
Header image credit: Ocean Image Bank / Jayne Jenkins