Apostrophes

Lots of people find difficulty with apostrophes, so if you're one of them then you're not alone.  Let's look at a couple of rules:

Apostrophes show where a letter or letters have been missed out.

Apostrophes show "possession".

These are the only circumstances when we use apostrophes.  Nothing else.  This is very important because people tend to use apostrophes in some other situations as well.

Omission

Omission is where something is missed out.  In the case of apostrophes, a letter or letters have been missed out.

Can't

This is really the word "cannot", but the "no" has been missed out.  Why?  No idea, but "cannot" sounds a bit too stuffy and old fashioned to me.  Omission often also includes the space between words (contraction), as well as some of the letters.

Where'd you go?

Here we've contracted the words "where did" into one word "where'd".  Because I missed out the space between the words and the "di" from "did", I've put an apostrophe in there to show it.

Possession

When we talk about possession in the case of apostrophes, what we mean is that one word belongs to another.

 

The cat's food.

Here the food belongs to the cat, so I've used an apostrophe to show it.

Potato's egg's veg

I saw this sign on the back of a van, but the apostrophe here is wrong.

The problem is, this doesn't fit with either of the rules that we introduced at the beginning.  The person who wrote this sign has used apostrophes to show plurals.  This is very important.  Apostrophes are never needed for a plural.  What the signwriter should have written is this:

With the word "potato" we add an "es" rather than just an "s" (we'll cover plurals in another lesson) but we still don't add an apostrophe.

Looking back through the lesson, can you identify why I've used apostrophes where I have?

Verbs

We use lots of words every day and lots of those words are verbs.  A verb is a type of word that tells us about something that happens.

The dog ate my homework.

I've highlighted the verb in this sentence.  The word "ate" tells us what happened.  The other words around it tell us who did it (the dog) and what they did it to (my homework).  Every sentence in English has at least one verb, because the purpose for writing or saying a sentence is to tell us about something.

Run!

 

Here we only have one word in the whole sentence, but that one word is still a verb.  It tells us about an action - running.

 

Verbs also give us an idea of "when".  The word "ate" tells us that the homework has already been eaten - it happened in the past.  "Run" is an instruction (also known as an "imperative verb", which we'll cover in a later lesson) and therefore is going to happen in the future.

 

The dog is eating my homework.
 





Here the action is happening right now.  It's still the dog eating the homework, but it hasn't already happened - there's a chance that we could get the homework back from the dog.

 

The dog will eat my homework.

 

The action in this sentence hasn't happened yet - it's a prediction for the future.

Addition - the basics

Addition is when we find the total of two or more numbers.  We can use counting to add two single digit numbers.

Let's imagine that a bookshop sells 3 books in the morning, and then sells 2 books in the afternoon.

If the owner wanted to find out how many books she had sold in total then she could count them up:

1... 2... 3...    from the morning's sales

4... 5...          from the afternoon's sales

Therefore, she sold 5 books over the course of the day.  What the bookshop owner has done is to add up 3 and 2.

3 + 2 = 5

We can use our fingers to add up single digit numbers.

3 fingers (well, a thumb and two fingers) represents the first three books.  Then put up another finger for the first book from the afternoon, and another for the second book from the afternoon.

Adding up is a very important skill.  You'll do lots of adding up as you do more and more maths.

Place value

When we write a number with more than one digit, each of those digits has a different value, depending on its position.  We call this "place value".

 

H, T and U mean "Hundreds", "Tens" and "Units".  Because the 2 is in the hundreds position here it's not just two, it's actually two hundred.  This is very important, because without place value we could never make numbers that are bigger than 9.

We can split this number up into its parts like this:

We can use place value to help us to convert numbers from digits to words and from words to digits.  For instance, take the number "three hundred and nine".  From the words we know that there is a 3 in the hundreds column, and another 9 units:

There's a zero (0) in the tens column because it wasn't mentioned in the words.

When we start to add, multiply, subtract and divide large numbers, place value becomes even more important, so keep that in mind.

See if you can convert these numbers into words:

207
720
217

And see if you can convert these numbers into digits:

four hundred and ten
seventy-two
one hundred and fifteen

The Atom

Atoms are made up of Protons, Neutrons and Electrons.  These are sub-atomic particles (things inside an atom, just like a submarine is a thing inside the sea).

Protons

Here's the chemical symbol for Aluminium, from the periodic table:

The number at the bottom is the Atomic number or Proton number.  This tells us how many protons there are in one atom of the element.  This is very important.  Take a look at your periodic table and you'll notice that every element has a different atomic number.  This means that the atomic number can't change - otherwise the element would be different.  And if we could do that then we'd all be turning everything into gold, right?

So we know that the atomic number can't change.  This is the number of protons in the atom.

Electrons

When an atom has no charge, and for now we'll assume they all have no charge, it has an equal number of electrons to the number of protons.  That's really useful, because it means that when we look at the chemical symbol for Aluminium, we know it has 13 protons and 13 electrons as well.

Neutrons

So what about neutrons?  To work that out we need to know what the subatomic particles weigh.

Sub-atomic Particle	Relative mass
Proton	1
Neutron	1
Electron	1/2000 (so small it’s practically zero)

Wondering about that 1/2000?  That means we'd need two thousand electrons to weigh as much as one proton or neutron, so we can ignore them when we're working out the mass of the atom.

The top number in the chemical symbol tells us the relative atomic mass.  This is how much the atom weighs.  Using this we can work out how many neutrons there are in the atom.  Let's look at Aluminium.  It has a relative atomic mass of 27.  We know it has 13 protons (which weigh 1), so taking those away from the total weight we're left with 14.  That's how many neutrons there are.

Appearance

What does all this look like?  The real answer is nobody actually knows - the atom is too small to see what it looks like.  Instead we use a model to represent it.  We'll look at the different parts again in a later lesson, but for now, here's a rough idea:

Ignore the word "orbital" for now, but here we can see 4 sub-atomic particles in the nucleus - 2 protons and 2 neutrons - and 2 electrons as well.  Using what we've learnt, can you identify the element?