Monday 1 April 2013

Measuring Angles : The Rule of 3 - 4 - 5

Hello Little Mathematicians!

 It's April Fool's Day! I'm just glad that none of you played a prank on the teachers.

Did you know that in countries like  Italy, France and Belgium, people tack paper fishes on each others' back as a trick and shout "April fish!" in their local languages?




______________________

As for maths lesson today, we covered the topic on measuring angles where Miss Dee taught you how to use a protractor to measure angles accurately. But the learning doesn't just stop there! Miss Dee would like to take you on a journey to explore the history behind angles. Did you know that the protractor has been invented 4,000 years ago? I wonder who invented it ...

Learning Points 

1) Protractor originates from the word "protract" which means to draw to scale.
2) There are four parts to the protractor : OBOI ( Origin, Base line, Outer scale, Inner scale)
3) How to use a protractor?
     Step 1 : Align the base line of the protractor with line 1.
     Step 2 : Slide the protractor along the base line til the vertex of the angle reaches the centre of the      baseline .
     Step 3 : Locate the origin ( where point zero is). From there, decide which scale to look at.
     Step 4:  Locate where line 2 is. Read the measurement off the scale.

Fun Online Games on Measuring Angles
( Click on the links below)

Measure the Angles by Mathsplayground

Kungfu Angles by BBC
This game requires you to estimate the angles in order for you to attack your opponent!


 Below are some questions for you to ponder.

1) Besides the protractor and the full protractor, could you name me other instruments or ways to measure angles?

E.g The Full protractor (which I've shown it to you today)


2) What are the advantages and disadvantages of using the protractor?

( As what Anan has shared during class, the protractor can't measure angles up to 360 degrees. Could you think of more advantages or disadvantages?)


3) Remember I mention about the rule of 3-4-5 ? It's a rule which people follow to measure out right angles accurately. But, how does it works?

Answer:

A triangle with a right angle is formed when the slanted line of the triangle measures 5 units, horizontal line measures (4 units) or vertical line ( 3 units).
Regards,
Miss Dee



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31 comments:

  1. Koh Xian Hui Bernice Koh Xian Hui Bernice Koh Xian Hui Bernice Koh Xian Hui Bernice2 April 2013 at 09:17

    Is there more than 360 dergress ??

    ReplyDelete
    Replies
    1. 4seven2 April 2013 at 20:11

      Good evening Bernice! One full turn gives you an angle of 360 degrees. It is possible to go beyond 360 degrees but that would means turning another round for the second time.

      Miss Dee

      Delete
    2. Anonymous2 April 2013 at 20:51

      So it means that there is no more than 360 degress ?? ^__^

      Delete
    3. ANDREW2 April 2013 at 22:17

      NO,TWO ROUND OF TURNING IS 360 DEGREE?IT IS 720 DEGREE!

      Delete
    4. Hazel Nut3 April 2013 at 20:20

      Andrew , please DO not TYPE in CAPITAL LETTER S!!!!!!!

      Delete
  2. YX2 April 2013 at 09:41

    Are there more protractor?

    ReplyDelete
    Replies
    1. 4seven2 April 2013 at 20:11

      It's for me to know and for you to find out.

      Miss Dee

      Delete
    2. Ben2 April 2013 at 20:43

      Again???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

      Delete
    3. Anonymous2 April 2013 at 20:49

      Who is Ben ?

      Delete
    4. Justice2 April 2013 at 21:01

      I am also rodent and student.

      Delete
    5. Ben2 April 2013 at 21:27

      Miss Dee I found out how many protractor are there.They are...
      Answer:
      FullCircle Protractors
      HalfCircle Protractors
      Square Protractors
      Rectangular Protractors
      Military Protractors

      Delete
    6. Hazel Nut3 April 2013 at 20:24

      I am going to expose Justice , Ben , YX , TYX , rodent student , Student 's identity . It is Yu Xuan !!

      Delete
  3. Eaint Phyu ( Emily )2 April 2013 at 09:58

    I do not think there are more than 360 degress .

    ReplyDelete
    Replies
    1. 4seven2 April 2013 at 20:12

      I agree with you Eaint Phyu. The maximum angle is 360 degrees. However, you can go beyond 360 degrees when you go for a second turn.

      Miss Dee

      Delete
  4. ANDREW2 April 2013 at 10:52

    Q1:we can use 2 rulers
    Q2:ADVANTAGE:we can use the protractor for better accuracy
    DISADVANTAGE: some people may not know a way to draw an angle
    using the pro tractor

    I KNOW HOW TO DRAW AN ANGLE USING THE PROTRACTER!

    ReplyDelete
    Replies
    1. 4seven2 April 2013 at 20:15

      Q1: Good suggestion Andrew! Yes, you could use two rulers to draw a right angle.

      Q2: If some people may not know how to draw, then perhaps you could teach them how to use it! That would be nice.

      Miss Dee

      Delete
    2. ANDREW2 April 2013 at 22:10

      BUT MS DEE, I NEED TO USE A RULER OR ANYTHING WHICH IS SRAIGHT.(MAYBE MY "SRAIGHT" IS SPELLED WRONGLY)

      Delete
    3. Miss Dee3 April 2013 at 09:51

      It is spelt as STRAIGHT. You are missing a letter 'T' over there.

      Delete
    4. Hazel Nut4 April 2013 at 20:03

      Miss Dee , why must Andrew type in cpaital letters !#?

      Delete
  5. Z I X I N G2 April 2013 at 21:06

    Miss Dee, yesterday i trick two teacher and they are Miss Zhou and Miss Atika

    ReplyDelete
  6. Z I X I N G2 April 2013 at 21:08

    they both fall into the SAME trick!!!

    ReplyDelete
    Replies
    1. Justice2 April 2013 at 21:09

      Clever

      Delete
    2. ANDREW2 April 2013 at 22:12

      Z I X I N G ,THAT IS NOT RIGHT THE (FOOL) A TEACHER,WHERE IS YOUR RESPECT FOR THE TEACHER!?

      Delete
    3. ANDREW2 April 2013 at 22:18

      "THAT IS NOT RIGHT TO (FOOL) A TEACHER,"

      Delete
    4. Emily5 April 2013 at 21:01

      What was Ms Zhou and Miss Atika reaction ? I would like to know if it is ok with you ? Z I X I N G *_^

      Delete
  7. Justice2 April 2013 at 21:08

    Zi xing,is the trick you did like saying their shirt are so dirty?

    ReplyDelete
    Replies
    1. ANDREW2 April 2013 at 22:14

      I DON'T THINK SO, BUT MAYBE IS THE DATE ,BUT ANYWAY , THAT IS NOT RIGHT!

      Delete
    2. Boy3 April 2013 at 08:34

      It is just a small trick that will make people laugh,it is not a trick to make people fell uncomfortable.

      Delete
  8. GYX3 April 2013 at 17:26

    Never mind it is all over. Stop arguing all over it!

    ReplyDelete
    Replies
    1. secret man 1353 April 2013 at 20:12

      Ok Goh Yee Xin.

      Delete
    2. Emily6 April 2013 at 09:58

      Who are you secret man 135 ? I have never ever heard of you . This is Eaint Phyu if you do not know who Emily is . m *_^

      Delete

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