Subjects

Some of our science studies this year revolved around a set of simple experiments to show what plants needed to grow and how they used those things. All these projects came from commonly available books or simply ideas that are familiar to most of us from our own school days. However, they were a lot of fun and coupled with an unusual summer of hot weather combined with torrential rain, which put paid to our normal gardening efforts, they gave us lots to talk about.

Growing an Avocado from its pip.

Apparently, an Avocado is a berry. Ours took a very long time to get started. We put it in warm water, in the airing cupboard for 24 hours and then left it propped on bubble wrap in a hyacynth vase for several weeks. Eventually after several top ups of water, it split but appeared to have no shoot, then just as we were about to throw it out, it grew!!! It stayed in our nice bright window until the root had reached the bottom and once it got as large as the picture on the right, it was planted out into a really big pot with lots of rich compost. its growing beautifully and looks most attractive and was a lesson in patience if nothing else!

Growing Beans in Different Environments

This was an excellent experiment, although i never took a final photo to show how good it got. The bean on the left had no light or water, the middle one had no water and the one on the right had water and light.

The one under cover grew but the shoot was quite white and didn’t know which way was up, the middle one didn’t grow at all and the one on the right did really well, with a tall, green, straight shoot. The girls were very interested in this and able to come up with excellent reasons for why it happened as it did. A great exercise in deduction and thought!

How Plants Drink

This was a very visual experiment and it happened so slowly that we were able to really watch what was happening over a period of days. I’ve done this before with less success so my hints for getting a good result are:

Use white carnations.

Cut stems really short.

Use about half a bottle of food colour to a small jar of water. The colour needs to be inky concentration rather than “lightly coloured water.”

Blue and green turned out to be excellent colours for this. The blue showed the colour moving clearly through the veins of the plant and the green separated a lot of yellow colouring from it, so the tips of the flowers were a different colour to the green in the veins. We loved this!

Growing Cress

Undoubtedly a real old favourite but fabulous for showing a child just what a seed can do when you add water and light to the food it has stored in its seed.

With thanks to June for supplying these excellent activities – if you have one to contribute – please let me know. June also runs HE-ED.

*IMPORTANT NOTE*

Kitchen science should be treated with the caution that all science is – and cleared away carefully to avoid children or animals having substances available in an uncontrolled environment. Please read packets of ingredients carefully and follow safety precautions. Better safe than sorry :~)

Making Flubber

Materials needed

Container 1

¾ cup warm water
1 cup white glue
food colouring (a couple of drops)

Container 2

2/3 cup warm water
½ teaspoons Borax

What to do
1) Mix the ingredients in each container thoroughly. Take note of how they both look, are they very different?

2) Pour the contents of container 2 into container 1. Lift and turn the mixture with a spoon until nearly all the liquid is gone. Gently squeeze any excess liquid from out of the Flubber.

3) What has happened? How does it feel? What happens if you stretch it? If you roll it in to a ball? If you place it over another object?

Polymers are made by a chemical reaction, they are long chains of repeating units. When the two solutions are combined, polyvinyl acetate chains (from the white glue) are linked together in a three-dimensional arrangement by Borate ions (from the Borax) and other chemical bonds. This produces the sticky polymer that we call Flubber.

Cabbage Acid-Alkaline Indicator

Materials needed

Pickled Red cabbage
Vinegar
Bicarbonate of Soda
A container

What to do

1) Remove the cabbage from the jar, as you only need the fluid that it was in.

2) Pour a little of the cabbage juice in to your container. Note the colour of the juice.

3) Put a small pinch of bicarb in to the juice. What happens?

4) Add a small amount of vinegar to the juice. What happens?

The colouring in the cabbage juice is an acid/alkaline indicator. When it is in an acid, such as vinegar, the juice turns red. When it is in an alkaline, such as bicarb, it turns blue-green. Do you have any other liquids that you could test?

Felt-Pen Chromatography

Materials needed

Felt-tip marker pens
Clear containers
Blotting paper
Water

What to do

1) Take a strip of blotting paper and choose a coloured marker pen (black works the best). About halfway up the strip of paper draw a horizontal line with the pen. Go over it a few times so that the colour is very concentrated.

2) Pour some water in to a clear container.

3) Dip the end of the blotting paper in the water, a couple of centimetres below the felt-pen line, and hold it as still as you can. What can you see happening?

4) When the water has travelled up to the tip of the blotting paper, place it on some paper towels to dry. What has happened to the felt-pen line? Is black ink really black, for instance?

Chromatography is the process of separating a mixture in to its components. The colour in the pens is made up of coloured substances, which have been dissolved in a liquid. When you colour with a felt-pen the liquid dries, and the colour is left behind. Therefore when the water creeps up the paper the dried colour dissolves again and is carried up the paper. Different colours are carried along faster and further by the water than others.
This works with mixtures other than felt-tip ink. Can you think of any times when this would be useful?