Rocks, vinegar and maps

I actually love rocks. I love the ones that are made when volcanoes erupt. I love the ones with fossils in and I especially love weird shiny spiky crystals. Where to find out more about rocks though? The study of all things rocky is called geology. The British Geological Society has a great website with lots of information. 


All about how rocks are formed


  This bit will show you all about the three types of rock - igneous, sedimentary and metamorphic. You can also see a map of Britain showing the types of rocks you find in each area. Which type of rock is your house built on? 


 The type of rock in your area will affect the water that comes out of your tap too! Soft water comes from igneous rock areas and is lovely and clear and pure. Hard water is full of minerals, like calcium carbonate, basically dissolved bits of rock. 


Have a look inside your kettle (not when it is full of boiling water...) and see if the inside is covered with white grainy stuff. That's called limescale and it's made of dissolved rocks in hard water. When the kettle boils, the calcium carbonate comes out of the water and sticks to the kettle. You might hear people complaining about scum on top of their tea - that's bits of dissolved rocks too! You can get rid of limescale in kettles using vinegar. Have a go - but ask an adult first... no one will thank you for making their tea taste of vinegar. Yuk! 


 Extra: Watch out for adverts on TV that talk about hard water. What other appliances like the kettle could be covered in limescale from dissolved rocks?

A rock game

Geology AND Sarah Jane adventures? What could be better?


Have a go at this game... and then have a think about the uses of rocks that you have seen in your environment, or even in another country. Do some places use more rocks in buildings?

Multiple multiples

Here's a game from BBC Bitesize about multiples and factors.

Sometimes people get confused about factors and multiples. They both relate to multiplying and dividing, but are in opposite directions.

The word multiple means many and sounds like multiply doesn't it? So if you multiply a number by something you get its multiples.

Multiples of 5 include: 10, 15, 30, 56 and...... think of some more...

Factors are numbers that you get from division. Think of a number.... hmmmmm... 24. 

24 has lots of factors because lots of numbers go into it evenly (without a remainder), like.... 12, 2, 6 and..... think of some more.

Now have a go at the game:

Extra thinking

What type of number only has two factors? Can you think of some examples?

What do salads and noses have in common?

I get dry skin, so I use a moisturiser to stop it getting dry and itchy. Here is a picture of me with a blob of moisturising cream on my nose. 

It's not a good look, is it? But it does smell nice, because I made it myself. Here is a picture of the cream in the pot. It's shame you can't smell it.

The ingredients of any moisturising cream are quite simple really. It's basically made of oil and water. You can use any oil, just not the kind you put in your car engine. And you can use any type of water: spring water, rose water (that's the stuff that gives turkish delight its smell and taste) or even tea, without milk and sugar of course. The tricky bit comes when you mix your oil and water together. Why? Let's try. (ASK FIRST) 

Get a glass of water and pour a teaspoon of cooking oil from the kitchen cupboard into it. Look carefully. 

What has happened? Can you dip your finger in a touch just oil? Or just water? 

It doesn't look creamy and blobby like my moisturiser, does it? The thing is, oil and water don't mix. The molecules that make up oil and water repel each other. 

What's repelling? Think about two magnets, they either pull together or repel each other so they are pushed apart. (TRY IT) 

Oil and water don't want to get mixed up to make my moisturiser. So I add an emulsifier. Let's look up emulsifier in the dictionary. Mine says, 

"Generally, any ingredient used to bind together normally noncombinative substances". 

What does yours say? 

So it's something we can add to make oil and water emulsify, or break up into teeny little bits that will make a smooth, creamy mixture. Nice and smooth, so I can rub it into my skin. I use an emulsifying wax. It looks like this:

Looks a bit like rice doesn't it? 

You can make oil and waters mix using force too. We don't usually encourage that do we? Shall we make an oil and water emulsion in the kitchen? One that you can use at home? It's actually a nice thing to make, but do ask someone before you do it.

Let's make salad dressing (also called vinaigrette). 

You need: 1 part vinegar : 3 parts oil (olive or sunflower or any kind of cooking oil) 

That means for every one amount of vinegar you add three of oil, giving you four parts altogether.

So, 1 spoon of vinegar and 3 spoons of oil, gives you 4 spoons of salad dressing. Or 1 litre of vinegar to 3 litres of oil (DO NOT MAKE 4 LITRES OF SALAD DRESSING AT HOME. YOUR FAMILY WILL NOT THANK YOU). 

So if we use 50ml of vinegar, how much olive oil do we need?

• Put your chosen amounts of oil and vinegar into an empty jar. You need one with its original lid. 
• Add some other ingredients for taste - salt, pepper, a small spoon of mustard, any herbs you like. Not jam. Jam does not taste good in salad dressing. 
• Look in the jar. What do you see? 
• Now. Put the lid on the jar very very tight. Shake the jar as hard as you can. What can you see now?
• After a really good shake you will have a thick, slightly gloopy looking liquid. The oil and vinegar have been forced to mix. You have emulsified them. You can now put your dressing on any kind of salad and eat up. 

Do not put salad dressing on your nose though. It won’t feel nice.

Extra thinking...

Emulsifiers are often used as additives in food. Anything that needs to stay nice and thick and gloopy will have an emulsifier in it. Look at some food labels, are there any emulsifiers in the ingredients? What are they?

Emulsifiers used as additives will have an E number. All food additives have an E number. See if you can find what range of E numbers are used for emulsifiers.

Time to think...

This is a painting by Salvador Dali. 

He lived in Spain in the 1930's. He's a surrealist painter. Let's look up surrealist in a dictionary. Mine says 

"Surrealism was an artistic and literary movement, dedicated to expressing the imagination as revealed in dreams, free of the conscious control of reason and convention" (Thanks www.artrepublic.com)

What does your dictionary say? And what does it mean? 

Well, you don't have to draw what's there. You can draw things from the inside of your head. It's all about your imagination. You can even draw your dreams; although some dreams, like the one about the giant fluffy diplodocuses, might be best kept to yourself... 

Anyway, here's one of Salvador Dali's thoughts in painting form. 

It's called The Persistence of Memory and it's a very famous image. You'll see it again and again, I promise. 

How does it make you feel? What do you think Salvador Dali thinks about time? Is time always the same or does it change? Why is the title about memory?

I think Dali's clocks look pretty relaxed. Clocks don't make me feel relaxed. If I drew imaginary clocks, they'd look a bit different. Why not draw a clock that shows how you feel?

Learn more about Salvador Dali using these links:

Wikipedia on Salvador Dali - remember facts on wikipedia should be checked. 

The Dali Museum in Florida has a lot of his works 

Brian Sewell is an art critic. Here are his quick facts about Salvador Dali. 

The Tate Gallery in London has these works by Dali 

Let's start with a game.