#copthallbigbangonline Stem Challenge! Monday 6th July

Posted on: 01/07/2020

Mr Taibi has set you some fun STEM challenges for the Copthall Big Bang Online on Monday 6th of July.  

Film, photograph or describe your attempts, send to Ms Sheridan and share it on social media #copthallbigbangonline 

1. Spagehtti Tower Challenge  

What you will need: 

• Spaghetti 

• Marshmallows  

Building towers out of spaghetti and marshmallows is a great way to think like an engineer. This STEM challenge is a simple, easy and cheap science activity, which can be done at home. You will consider the properties of objects, the factors that contribute to stability, and the importance of testing things out. A good structure must be stiff and strong, able to take a lot of force before it collapses. Different shapes have different strengths and weaknesses. Experimenting with squares, triangles and other shapes is a great starting point for thinking about the process of building things like houses and bridges. 

Watch here: 

2. Homemade Lava Lamp 

What you will need:  

Large container for water, a bucket, plastic tub or even a mixing bowl. Or you can use the kitchen sink or even do the activity in the bath.  

Collection of objects to test whether they float or sink. For example cutlery, cookie cutters, fruits and vegetables. It’s a good idea to have different sized versions of the same thing, like tomatoes. You could also test the same thing made from different materials, like a plastic spoon and a metal one.  

• Oranges or lemons or grapefruits 

• Tin foil (to illustrate density)  

• Can of soft drink and a can of diet version of same drink  

• A tall glass or empty, clear plastic bottle for the lava lamp  

• Some vegetable oil.  

• A few drops of food colouring  

• Water  

• An alka-seltzer tablet or a fizzy vitamin tablet. 


What to do:  

Make a prediction as to whether the objects will float or sink.  

Demonstrate the idea of density – Loosely roll up some tin foil into a ball. Try it out in the water (it should float). Squeeze the ball up as tightly as you can, giving it a real squashing as Olympia does in the video. Then ask yourself what you think will happen and why. Try it out.  

Try out citrus fruits – See what happens to a citrus fruit when it has its skin on and then when it has been peeled.  

Try out cans of original and diet versions of a soft drink. 

Make a lava lamp – Using the tall glass or empty bottle, fill it about a third full with water. Then top it up with vegetable oil. Add a few drops of food colouring. Wait for the colour to mix in with the water. Break an alka-seltzer or fizzy vitamin tablet into quarters. Drop a piece of the tablet into the glass and watch what happens. Add more pieces of tablet if you want more bubbles.  

Questions to ask yourself:  

Before each activity: can you predict what will happen? 

Why do you predict that? 

(For example, can you predict what will happen when we squash the tin foil really tightly?  

Can you predict what will happen if we use metal spoon instead of a plastic one?  

Can you predict what will happen if we peel the fruit?)  

Why does the diet drink float while the non-diet one sinks?  

What do you think will happen when we pour the oil into the glass of water? Why?  

What do you think is in the bubbles that are rising up in the lava lamp?  

Why do you think they sink back down again? 


The Science:  

To understand why some things float and others sink, it’s helpful to know about the concept of density. You can think of density as how ‘compact’ something is, or how much mass of something you have in a given volume.  

Density is defined as mass divided by volume. Something that is more dense than water will sink, something that is less dense will float.  

The lava lamp works as Olympia describes it in the video. The alka-seltzer tablet reacts with the water to produce bubbles of gas. These are less dense than the water and oil so they float to the top of both liquids, taking some water with them. When they reach the top of the oil, the bubbles burst, releasing the gas so that the water sinks back down through the oil.  

Risk Assessment:  

Alka-seltzer tablets contain sodium bicarbonate, aspirin and citric acid. They should not be eaten by children. The lava lamp contents should not be drunk.  

Watch here: 

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