Science club – Digestive system

Week Two – Digestive System

Arrival Craft: Paper digestive system from Scholastic model book

Introduction: What does our digestive system do?

It reduces food to simpler parts, then distributes it around our body as required.

Does anyone know how we get food from our intestines into the parts of our bodies that need it? We use something very clever called osmosis.

Osmosis is basically about fairness. Substances move from an area of high concentration to an area of low concentration. Just like, if I gave this table a big bowl of sweets and no sweets to the other tables, this table would share the sweets out until everyone had the same amount.

Our bodies don’t need to work for osmosis to happen, it doesn’t take any energy. Things just move from where there’s lots of them to where there isn’t much.

If I put a drop of very sugary water into this bowl of plain water, what will happen? The sugar will spread out until all the water is equally sugary.

That happens in our bodies, and it’s a very important part of how we get food from our mouths to the rest of our cells.

We’re going to do an experiment to show how osmosis happens in our digestive system.

I’ve got three liquids here. I have plain water, sugary water and starchy water.

They all look pretty much the same.

Does anyone know how we can tell if water has glucose in it?

Does anyone know how we can tell if water has starch in it? (We covered this a while ago in our food week, so some of the children remembered.)

I also have some sausage skins. They’re made of something very like your small intestines.

You can see that water cannot get through the sausage skins. It doesn’t drip out.

But, there are tiny holes in the skins and some molecules – which are smaller than water molecules – can get out.

You’re going to do an experiment to discover whether glucose or starch can get through the sausage skins.

Individual Task – Set up sausage skins filled with glucose and starch mixture. Immerse them in water. Test to see if starch and/or glucose can get through the sausage skin. sausageskinexpt

 

Second Half: Show anatomy model.

Our digestive system is divided into several parts. It moves from our mouths all the way down to our bottoms. Get a child to wear the digestive system apron (I found this online, it’s brilliant fun) and see if the other children can name all the organs of the digestive system.

Individual task: Give out plastic aprons and sticky-backed organ pictures so that the children can make their own digestive system aprons. digestivestickers

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