Did you know that a blue whale’s tongue can weigh as much as an elephant? Yes, that’s right. The blue whale is the largest animal that has ever lived — it’s bigger than an elephant and even bigger than every dinosaur discovered.
But why do so many of the large animals, like whales, live in water? Little Scientists has developed the hands-on activity below to support children to explore:
- Why water makes heavy objects feel lighter.
- The STEM concepts of force, buoyancy and gravity.
- How whales have evolved to grow so big.
Don’t forget to share your STEM explorations with us! Join Little Scientists’ Facebook group “Early STEM Educators Network” to exchange STEM ideas with educators all over Australia.
Activity
Equipment:
🐋 Water
🐋 Rocks
🐋 A large bowl
🐋 A strong plastic bag
Instructions:
- Give the children an opportunity to marvel at the sheer size of a whale. You can show a short video or a picture of different types of whales.
- Put a handful of rocks into a plastic bag. This is your “whale”.
- Invite the children to try to pick up the full bag. It’s so heavy!
- Place the bag in a bowl with water. Tie the bag up so none of the water goes inside.
- Encourage the children to try to lift the bag of stones again. Did this feel different than without the water?
The children probably found that the bag felt lighter and easier to lift when it was placed in the water. That’s because the water pushes the bag of rocks up from underneath. This is called “buoyancy” and acts against gravity, which is the force pulling the rocks down when the bag was not in the water. Buoyancy makes the bag of rocks feel less heavy in water. It’s buoyancy that supports whales to grow large as they don’t have to support their weight on legs or against gravity, like land animals do.
Extension ideas
Explore this force with a few extension ideas after you’ve tried the whale weightlifting activity:
🏊♀️ Ask the children to reflect upon how they feel when playing in water. Do they sink or float? Do they move faster or slower than when they are on land?
🏋️ Have children sort different objects by weight, such as toys and blocks. Do bigger objects always feel heavier?
🦭 Show pictures of other large animals like elephants, sharks, and hippos and invite the children to sort these by order of weight. You can also ask them to sort the animals into different categories, such as number of legs, height, and even colour.
🌊 Try the weightlifting activity but this time, replace the rocks with different items such as feathers or leaves. Encourage the children to reflect upon how these experiences compare to using rocks.
🛥️ Pull different objects such as toy animals through a tub of water and observe their drag along the water’s surface. Take this opportunity to investigate how the shape of objects can also affect their buoyancy.
Develop your STEM skills with pedagogy-based STEM PD:
- Browse our in-person STEM workshops.
- Browse our online STEM workshops.
- Browse our online STEM Hours.
- Book an in-service workshop for your team.
- Book a STEM Family Workshop for your families.
