Wednesday, April 22, 2009

Equivalent Ratios.

Today's lesson will be simple if they know how to change fraction into simplest forms. Hence, the concept of equivalent ratios is almost similar to equivalent fractions.~

The only difference is that while fractions is written "up and down", ratios are written in "left to right"

Watch the video to find out how similar fractions are to ratios.



*Side note: I will be staying during recess time to help pupils who wish to learn or those who do not understand the concepts and need help.*

Mr Xie.

Monday, April 20, 2009

Ratio.

Class 5-5 learned all about ratios today.
I adopted an unusual way of teaching today. It was an eating lesson!

Pupils were divided into 10 groups and each group was given a pack of chocolates.
They are asked to open them and pour out the contents of the chocolates.
Red, brown, yellow, green chocolates were all over their tables and they were asked to make a list of how many they have.

Turns out that some packets have 9 while the others have 8. Hmmmm... something wrong with the chocolate-maker factory?

Then, I asked a question. What is the ratio of red chocolates to green chocolates. I was glad that each group was quick to provide me an answer. This shows that they have grasped the concept of ratio!

Some more ratio concepts that class 5-5 should know,
1) There is no need to write units for ratios.
2) The ratio has to be respectively represented as asked by the question. This means that if the question asked ratio of boys is to girls in class 5-5, one would have to write the answer as 21 : 20 and not 20 : 21.
3) Ratio, similar to fractions are to be converted to the simplest form.

I was glad that the lesson went well and I hope that students have enjoyed and learned or at least grasp the concepts of ratios today.

*Oh, what about the chocolates? Students ate them all of course!" I was lucky to have one piece. Yum Yum.*

Mr Xie.

Wednesday, April 15, 2009

Area of triangle. Version 1.1a.

After marking their work on area of triangle today, I realised that quite a number of pupils still doesn't know how to identify the height and base of the triangle given to them.

I know that it's confusing for most of them but I hope the things that I teach; students will be able to use the strategy and learn the concept.

To find out the base or height of the triangle, one must always keep in mind that Base and Height are always perpendicualr to one another. It is always 90 degrees. The lines will always be like a "L" shape. This is a fact and will never change.

Here onwards, I will be explaining how to determine the base and height of a triangle. (This will be explained in greater detail tommorrow.)

1) Once you get hold of the diagram, shift and rotate your paper so that the base is lying horizontally. (Left to right). Once this is done, do not rotate the paper anymore.

2) Once it is positioned correctly, and due to the fact the base and height is perpendicualr to one another, we now can deduce that the height is confirmed going vertically (down to up) from any point on the base.

3) Since we know that the height is straight down, we now look for the highest point of the triangle. Once we locate where it is, draw a straight line down.

4) If it touches your base, Volia! You have the height and base of the triangle.
If not, extend the base so that it meets.

That's all to it for finding the base and height.
I know it's confusing to explain it in words , hence I will be explaining this in greater detail to you for the next lesson.

If by chance, pupils of class 5-5 are reading this blog, you might want to prepare 2 - 3 random sized triangles (Make a relatively big triangle) so that I can share the above idea with the class tomorrow. Thanks.

Mr Xie.

Tuesday, April 14, 2009

Area of Triangle.

Today's lesson was straightforward enough, finding the area of triangle.
We all know that the forumla for area of triangle is,
base x height divde by 2. or simply.
What we do not know is why is it half? and not one-quarters or one-fifth?
Watch the video below to find out.

Monday, April 13, 2009

Base and height or triangle.

Finally, after resting for so long, a blog post! Thursday was a school event, "Olympics carnival." followed by a public holiday and the weekends. Hence, blogging about school lessons was postphoned for a short while.

Today, class 5-5 learnt about how to identify the base and height of a triangle. To us adults, identifying the base and height is just like walking. It comes so naturally when we take a look at the diagram. However, this is not the case for students.

As this concept depends heavily on the students' visualisation skills, it is very hard to explain where is the height and base of a triangle.

After thinking it long and hard after the lesson, I decided to make use of a common ruler to help identify base and height.
Use a marker and draw the same thing as I did as shown below.
Now, you have a self-made a height/base identifier tool. How do you use it?
If the diagram tells you where the base is,use the line on the ruler to match the base first. The perpendicular line will then be the height of the triangle at it's highest point.

I hope this "mini-tool' will help students to identify the base and height more easily. It's good because you can bring this into exams! :)

Mr Xie.

Sunday, April 5, 2009

Fractions involving division.

Since the class has learnt addition, subtraction and multiplication of fractions, there is no reason not to learn division of fractions. Right?
To do division of fractions, it is as simple as multiplying fractions. This means that if the class can manage multiplication of fractions well, they are definitely able to do division of fractions.
Here are some steps to help you remember when attempting division of fractions.
1) Rewrite the problem.
2) Change the division sign to a multiplication sign (important*)
3) "Flip" the 2nd fraction. (If it happens to be a whole number, "add" a "hat" for it. *Class 5-5 should be able to understand what I mean*)
4) Do the problem as a multiplication problem now.
5) Done!

The video below shows you how to do division of fractions involving proper fractions and proper fractions.

For the next lesson, I think I should tell the class or re-teach the division of fractions once more using a funny storyline that I came up with. This is an important concept and I hope that all students are able to understand it completely.

Mr Xie.

Wednesday, April 1, 2009

product of a mixed number and a whole number.

Class 5-5 learned how to multiply a mixed number and a whole number today.
The trick into sucessfully do this question is to convert the mixed number into an improper fraction. How do we do it? Take a look at the video to learn the fastest way to convert a mixed number to an improper fraction.



After learning the concept of today's lesson, students were transformed into police officers as a bomber has run loose! He has placed different bombs all over the city and it's 5-5's duty to stop him? Luckily, we managed to find out where the bombs are even realised there's a mole hiding amongst us. Finally, he revealed the whereabouts of the missing bomb.

I hope the students have fun from this activity that I created specially for them. I was pleased that they behaved well when there are visitors around. keep up the good behaviours! class 5-5.

Mr Xie.