“Why does my banana skin go brown when I peel it off? asked Gina (10)

Gina, it seems to be something about the ‘breaking’ of the skin of the fruit, which lets  in oxygen and allows it to react with some of the fruits chemicals.

We could test that idea. One way to test it might be to try and stop the ‘breaking’ of the skin of the banana. Can you think of a way of removing the skin without breaking or damaging it?

We could also test the role of oxygen. Any ideas how? If you have an idea why not try it  by comparing the speed of ‘browning’ for your oxygen and ‘no oxygen’ banana skin?

Remember to try and make the tests as fair as possible. Think about what that may mean. Remember a fair test means only changing one thing at a time while you try and keep all other things constant.

Let me know how you got on by Leaving a Reply in the box below.

“How are sounds made?” asks Mohammed (7)

Thank you team. Some of the things in the image above make sounds without tapping or blowing. Can you find them? Miwah asked a similiar question where he investigated how the sound a drum made was created. Can you try an make a sound using a ruler. Try holding one end of it on the desk and then bending it slightly by pushing down on the end which is not resting on the desk.

Now let go ….. and here come the questions.  Did you hear anything? What did the end of the ruler do? If there was a sound when did it stop?

Another question. If there was a sound what part of your body detected it? So how did the sound get to you? What is between your bodies sound detection and the ruler?

Now for a little bit of information. How did the ruler move when you let go of it? The word to describe this movement is ‘vibration’. A vibration is a continuous small movement up and down, or side to side. This is what Miwah discovered in the drum investigation. Below is a small video of a plastic ruler being pushed downwards and then allowed to vibrate.

Investigate making other objects making sounds and see if you can ‘feel’ the vibrations.

Any more thoughts , then please make a comment or ask another question.

Ava (7) asks “Why do mirrors change words ?”


Ava, can you see how the image of the dog in the mirror is different from the dog. Look at the dogs raised ear. What side of the head is it on? NOW imagine you are the dog in the mirror, what side of the head is the raised ear on.

Try this, look in a mirror and point your right finger at the mirror. Now try to put yourself in the position of you in the mirror and what side of you is your finger. Is it your right finger or left finger, in the mirror???  Wow. The mirror has inverted your image (the dictionary says inverted means  – put upside down or in the opposite position.)

Now try a mirror with some words. Try it with this word  Mirror Me. Write it on a piece of card or paper and look at it in a mirror. What does it look like …..is it like this?

Think about what you are seeing. Why can you see the image in the mirror? Think about reflection? This is a very difficult area of understanding BUT you can have a lot of fun with it.

Updated 12/6/17

Preethikha (13) asked a question about planting corn seeds in clay.

Preethikha you asked your question on behalf of your friend  Johan who appeared to be having trouble in growing his corn seeds in clay. I asked my friends about this and these were the ideas that they arrived at. 

The roots of the corn plant are very complex like most plants and they NEED oxygen . Clay is an important soil, it is full of nutrients which are important in providing the growing plant with food , HOWEVER  it is very different from most of the soils that we meet in our gardens.

Soils are composed of three types of particles: sand, silt, and clay.

The size of the particles varies, with clay having the smallest size and sand the largest.Smaller sized particles pack more closely together and slow the flow of water through the soil.The composition of a soil can affect the permeability (flow) of water through it.

There is the possibility that your friends corn seeds produce roots which are then ‘drowned’ in the surrounding clay soil. Investigate your friends soil and compare it to other soils in your neighbourhood. My next question for you is how would you go about investigating it ?

 

“Why does every country have different plug sockets?” asks Harry (10)

Thanks team. The third socket, the Earth socket is sometimes called the ‘grounding socket”. Lets try to make our own circuit to find out a little bit about this.

You would need a battery, some wire, a light bulb in a bulb holder and let’s say a cup with some damp sand in it.

 

Push the earth wire into the wet sand and see what happens.

The Earth socket on a UK plug is designed for problems where the electricity that you are using becomes unsafe, for example a wire inside a washing machine touches the case that the machine is contained in. The case it attached to rubber, non conducting wheels. You touch the case, with your leather soled shoes and you then get an electrical shock. If the case is attached to the earth wire the electricity finds an easy route to escape and this causes safety switches to open in the fuse box of the circuit. In the old days it would make a fuse melt and thus break the circuit.

The Earth socket is therefore a safety socket. Lots of appliances nowadays are so well insulated (protected) that an Earth protection is unnecessary. Some plugs have a plastic third pin. Two pin plugs have never had this additional protection.

Another experiment that you might like to try is changing the wet sand for other materials. Try leather, metals, china, dry sand, cloth ….. all sorts of materials. What an experiment! Brilliant.

DO NOT EXPERIMENT WITH MAINS ELECTRICITY

(updated 18/5/2017)

James asks “What happens to the cactus flower the day after it flowers?”

Many thanks team you are right. The cactus needs it’s flower to be pollinated.

What do I mean by pollination?

Lets look at that picture more closely (see below). Pollination is the process of transferring a pollen from the male part of a plant (the anther) to the female part of the plant (the stigma). It is better that the transfer process is from the male part of one plant to the female part of another similar plant.

What helps this happen – Bees, flies, bats and lots of other insects.

What happens then – A fruit develops from the flower site and in the fruit are seeds, lots of them. These fruits are eaten by animals and by this method the seeds are spread around the surrounding environment.

What experiments could you think of to test these thoughts (hypothesis)? Any idea then click on the ‘Leave a Reply’ button below.

“I know I can see myself in a mirror but why cannot I see myself in other things?” asks Isabella (8)

Many thanks team. I have some ideas about investigations that you could do at home. People say that light travels in straight lines. How can we test this idea. Firstly we need a source of light. How about a torch. 

Now we know that a torch sends out light in all directions but how do we know if it is travelling in a straight line? Think……..

Now lets ‘capture a little bit of the light from the torch. Let’s use a piece of card with a hole in it and see if we can make the light from the torch go through the hole.

Now what do we have to do to show that, the little beam of light coming through the hole is travelling in a straight line?
Supposing we had another piece of card with a hole in it in exactly the same spot do you think you could arrange it so that the little beam of light goes through the hole in the new piece of card?

Do the same for a third piece of card arranging it so the little beam goes through it’s hole. Now draw a line between the torch and the third hole. What do you notice?

Now lets quickly look at your question about not seeing reflections in materials that are not mirrors.

Reflections are wonderful things and they happen, or do not happen because light travels in straight lines. A reflection occurs when a beam of light bounces off a surface. You could set up your torch and card above to make a reflection, using a mirror or something flat and shiny.

Now do the same for a different type of surface.try it with a piece of material. What happens? Try with all sorts of flat surfaces – shiny metal (use flat aluminum foil and then crinkle it), cardboard, paper, plastic, water, leather……..
What do you notice? Maybe reflection requires a flat shiny surface? Think about the results.

Liam (10) asks “Why does electricity go around a circuit?”

 

Thanks for that team , a very informative introduction. It’s usually the furthest electron that is involved in moving the electrical energy around the circuit.

I have tried to create a small animation to show how this might happen. The ‘pipes’ are the copper metal wire. the dots are the outermost electron attached to the numerous copper atoms. The battery is the ‘motor’ that makes the electrons move. To find out a bit more about how the battery work have a quick look at Sadies question.

Electrons are negatively charged particles so the negative terminal of the battery is ‘pushing’ the electrons while the positive terminal of the battery  is ‘pulling’ the electrons SO when the switch is closed all the electrons in the circuit start moving together.

Who do you think discovered that opposite charges attract and negative charges repel?

Now what about the filament in the bulb. Any idea why that starts producing light? Any thoughts on both these questions, let me know in the ‘Leave a Reply ‘ box.

 

 

“How do you measure the distance to the Sun and stars?’ asked Julian (12)

 

Julian, quite a challenging question. I will only be trying to answer the first part – the Sun-Earth distance and the Earth-Stars distance.? Even then as my team suggests, I might be introducing mathematical terms that you have not met yet, but I have included links to other sources of help.

To answer the first question I recommend you read a Universe Today article   It is an excellent historical review of the problems that the early scientists had in determining the Earth-Sun distance. The answer finally came from observations of the movement of the planet Venus across the face of the Sun. In it the writer refers to a Nasa document that tries to explain the methods used. In present times the distance to the Sun is measured by ‘bouncing’ a radar pulse of of it.

Determining the distance to the other stars becomes possible once the Earth-Sun distance was known. It uses a technique called parallax.  I would like to illustrate this with a question which tackles a simpler problem. ‘How far is my finger away from my nose?’

Try this little experiment, put a finger in an upright position in front of your nose. Now close one eye and note the position of the finger. Close that eye and open the other one. The finger moves! Now suppose, with help, you could measure the amount of movement. You could end up with diagrams like those below. Did you make a note of the position of your finger relative to your nose? No – you can now see how you could work this out.

Now let’s do a little geometry and add an axis

We can then measure the angle of the apparent movement

You end with a right angled triangle ABC, knowing the angle x AND the distance between your eyes you should be able to do a bit of trigonometry using TAN x = opposite/adjacent (Tan x = AB/BC) and work out the distance of your finger from your face. For an introduction to trigonometry please look at this site.

Amazingly this is (in a crude way) the same process by which astronomers can measure the distance to the stars. Instead of using the distance between your eyes they use the orbit of the Earth. They look at a star and make a note of it’s position and then do the same thing 6 months later when the Earth is at the opposite side of the Sun. They therefore have AB (the distance between the Sun and the Earth and they have the angle through which the star has apparently moved. 

This gives the route to determining the distance between the Earth and a Star.

 

(revised 14/05/17)

 

Elizabeth (9) asked “How doesn’t stainless steel stain?”

Elizabeth I would like you try an experiment. Gather together some different nails. If you can, find a stainless steel nail, steel nail, iron nail and as many different nails that you can. Try and get two of each. Find two jam jars and put one set of clean nails in one jar and the other set of clean nails into the other jar. Why do I suggest cleaning the nails?

Fill the first jar with tap water and the second with water that has been boiled and cooled. Cover both with cling film and leave for about 7 days. What happens ?????

Relook at what you did at the start. What did  you see in the tap water that you added? How did this compare to the boiled water? What did you see when you boiled the water?

Most of the stains on metals are caused by interactions with water and oxygen.

When steel and iron are attacked on their surface by the oxygen from the water you get  things called oxides created as the oxygen (a very reactive gas) reacts with the metals surface. For most metals the compound (oxide) that is formed is fairly ‘soft’ and is washed away creating new sites for oxygen attack. With stainless steel it is the chromium in the stainless steel that reacts with the oxygen creating an invisible layer of Chromium Oxide and this is such a hard substance that no other substance can stain the steel.

If you rub the stainless steel implement hard with a scraper you might get rid of the strong oxide and create a stain by attacking the surface of the steel with another substance. Try it (with permission).

Elizabeth and others, quite a detailed answer. If you want to ask further questions please ask.