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Saturday, 23 September 2017

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Page 9 of 16

This term we are concetrating on our times tables along side our other areas of maths, We have already discovered how knowing our times tables perfectly can make the rest of our maths so much easier. Remember, no matter how much practice we do in school, doing a little extra practice at home will give you that extra boost!

This website is good for a quick practice. Click on it to have a go.

Each week, a maths problem will be put on this page. It is intended to help us have a think about a harder maths problem, and perhaps discuss with others at home. Remember, they are challenging!

Shape and measures.

This half term we have been looking at shape properties by identifying the differences between regular and irregular polygons.

**Polygon** comes from Greek. **Poly-** means "many" and **-gon** means "angle".

Polygons are 2-dimensional shapes. They are made of straight lines, and the shape is "closed" (all the lines connect up).

Polygon (straight sides) |
Not a Polygon (has a curve) |
Not a Polygon (open, not closed) |

The children created polygon shapes using the Mathsisfun website (link below) and described their properties.

**Have a go yourself and describe the properties of shapes that you create.**

Imagine unfolding a box so that it is flat. The result is the net of the cube box. There are some examples of different shape nets.

As part of our work, the children have looked at some examples and have solved some tricky problems to identify working nets and have even completed patterns on the faces to create a decorated cube.

Try this website to view and test your visualisation skills of 3D shapes and nets:

https://www.mangahigh.com/en-gb/math_games/shape/3d_shapes/nets.

The word perimeter comes from the Greek words, peri (means edge) and meter (means measure). The perimeter of a shape the measurement around the edge of a shape, useful if you want to work out how many metres of fencing you need around your garden.

To work out the perimeter of any shape, just simply add up all the measurements of the shape edge. In class, we spent a few days working on compound shapes (made from rectangles), finding the missing measurements then calculating the perimeter.

Example Compound Shape

Here, we have an example compound shape.

The first thing that you need to do is to split the compound shape into rectangles. This will help you visualise the parallel lines required to help identify the missing lengths.

The first length we need to find is top to bottom.

We need to look for clues to what that length could be. We know that it is parallel to the 3cm line and the 5cm line. If you put them together they would be exactly the same length as the missing length. So, we need to make an addition ..

The missing length is therefore 8cm.

Now to find the other missing length. You need to look at what you already know. The lines parallel to it measure 10cm and 4cm. Because we have some of the length then we need to do a subtraction ..

To find the total perimeter we need to make some additions ..

In Y6 however, children are expected to calculate the perimeter of any shape - just remember to add up all the measurements of every side.

The formula for working out the area of a square or rectangle is: Area = length x width.

Similarly to working out the perimeter of compound shapes, first split the shape into the rectangles. Work out any missing measurements and calculate the area for each rectangle. Don't forget to add the areas together to find the overall area of the compound shape.

For example:

Now, what you need to do is look at your shape and you need to split it into rectangles. I’m going to draw a line here and we have rectangle A and rectangle B.

To calculate the area of a compound shape you need to know the Length and the Width because these are multiplied together to equal the Area.

For shape A you already have a Length and a Width (it’s not to scale!) but you already have it. 3cm times 3cm equals 9cm squared – that was pretty simple!

However, shape B you’ve only got one measurement – 10cm times something equals something. What you need to do is to use the figures that you already have to calculate the missing Width.

The numbers that you’re going to be looking at are the numbers which are parallel to the line which has a missing width. This is parallel and so is that.

If that length from start to end equals 3cm then so must that part for that whole entire length. All together, that length from here to here equals 5cm. So if that is 3cm, then you must add 2cm to that to make 5cm.

You’ve just figured out using the parallel lengths that of the missing length.

Rember that the area of a right angle triangle is half of the area of the rectangle it makes.

So the formula is Area = ^{1}/_{2 }length x height or alternatively Area = length x height 2

**Which of these triangles has an area of 4.5cm ^{2}?**

**Can you name all the types of triangles and explain their differences?**

Answer to the Q above: they all do!

This formula works with all types of triangles.

If you know the area of a triangle and one of the measurements, you can use the formula to calculate the missing measurement. Why not test yourself or teach a family member, by trying this challenge:

**A triangle has a length of 12m and an area of 30m ^{2}. What is the height of the triangle?**

**Remember that The Big 4 operations below are central to most areas of maths and need regular practice.**

The **BIG** 4

**Addition**

Column addition works with any number, even decimals! Click on the sum to see a decimal addition worked through.

**Subtraction**

Column subtraction also works with any number, so long as you have the biggest number on top. Click on the sum to see a decimal subtraction worked through.

**Division**

We have learned 2 main ways of dividing, starting with chunking. Click on the sum to see an example worked through.

**Multiplication**

We know several ways of doing multipication but here is the grid method.. Click on the sum to see an example worked through.

Websites to help us improve our maths:

Practising your maths at home, even just 20 minutes every night, will help you become more confident with maths in school. Try these websites:

**This week's maths problem: **

Think of a number… multiply it by three… add one… multiply this by three… add the number

you first thought of… add two… take away five… divide by ten… and the answer is…

*Lateral thinking*

A 26cm x 26cm square metal plate needs to be fixed by a carpenter on to a wooden board. The carpenter uses nails all along the edges of the square such that there are 27 nails on each side of the square. Each nail is at the same distance from the neighboring nails. How many nails does the carpenter use?

104

It was Cheryl's first day at school. The teacher suggested that it would be a good idea for each child to meet every other child in the class. The teacher said, "When you meet, please shake hands and introduce yourself by name."

If there were 7 children in the class, how many total handshakes were there?

21

Last weeks answers:

If you were alone in a deserted house at night, and there was an oil lamp, a candle and firewood and you only have one match, which would you light first?

The match!

**What is the next letter in this sequence J F M A M J ?**

**J. They are the first letters of the months of the year!**

**A five letter word becomes shorter when you add two letters to it. What is the word? **

**Short (5 letters) er (2 letters) = shorter**

*