It is Experiments Day with My Students!

I have 2 students who are brothers, whom I teach Mathematics and Science as their part time tutor. I see them once a week for 2 hours and we had just finished some intensive classes to prepare them for their exams.

When I just went the past week, they requested to pause on academic studying and revision and wanted to have a break to do some experiments so I thought that is a great idea because due to the pandemic, the school has stopped all laboratory works and practices. This has caused study and learning to be monotonous and they cannot practise hands on for the theories they have learnt.

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So we did a few experiments today, some of which failed due to insufficient materials and apparatus but we still had a great time trying. These 2 boys have become less active after studying from home for almost 2 years so it is time to get them to move!

First we did the volcano experiment of mixing the baking soda with vinegar and added on a red food colouring to make it look real. I initially only wanted to demonstrate it in a bottle but my enthusiastic students wanted to make the side of the volcano as well so we took up some time to do that. However, they ended up with no paint and watercolour at home so it looked as if it is half way done again. Nevertheless, the volcano still "erupted" a little but we ran out of vinegar so it didn't fill up the whole bottle to have a more "vigorous eruption".

Aftermath of the eruption

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Corn starch with coloured water

I think my students had the most fun with this though I did not manage to take much photos of it as I too was feeling the texture between solid and liquid and my hands were all messy. Oobleck is another term of what this is called from Dr. Seuss.

Basically, it is just mixing the coloured water with the corn starch. Feel the corn starch texture first to remember how it is like. Then add water in bit by bit until all the powder is wet. Keep adding water until the oobleck feels more like a liquid. Then try using your finger or spoon to tap the surface and feel if it has become like solid.

Let this
SCIENCE BOB explains:

Our cornstarch goo (sometimes referred to as “oobleck” from the Dr. Suess book) is what scientists call a “Non-Newtonian” liquid. Basically, Sir Issac Newton stated individual liquids flow at consistent, predictable rates. As you likely discovered, cornstarch goo does NOT follow those rules – it can act almost like a solid, and them flow like a liquid. Technically speaking, the goo is a SUSPENSION, meaning that the grains of starch are not dissolved, they are just suspended and spread out in the water. If you let the goo sit for an while, the cornstarch would settle to the bottom of the bowl. So why does this concoction act the way it does? Most of it has to do with pressure. The size, shape, and makeup of the cornstarch grains causes the cornstarch to “lock-up” and hold its shape when pressure is applied to it. People have filled small pools with oobleck and they are able to walk across the surface of it (as long as they move quickly.) As soon as they stop walking, they begin to sink.

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M&Ms and Water

This experiment is to show how sugar dissolve in warm water and how the colours from the M&Ms coating decolourize. Within seconds after warm water is poured in the center of the plate, we can see the colours move towards the center of the plate.

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Making the salt sweet
Pour a little salt onto the plate and taste it. It should be very salty.

Add some tablespoons of flour and mix the flour and salt well.

After mixed it well, try tasting it again.

The mixture will taste a bit sweet because salt enhances the degree of aggregation of starch molecules in the flour. Starch is a form of sugar or carbohydrates so as the starch molecules being broken down, it will make the salt taste "sweet".

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Overall we had a fun time though we did wish we have more materials at home. Before the class ended, we spent some time watching some home experiments on videos and the boys got very intrigued by them. This is what I like to see - curiosity in learning and the joy of discovery!