## Wednesday, 31 July 2013

### Linear Graphs - VMC

THE VENDING MACHINE

The above shows a Vending Machine.
Basically there is an input and an output.
It is a one to one function.

1. What are the assumptions made in designing of the vending machine.
2. If a drink cost \$1.50, draw a table of values to show number of bottles against cost.
in the following format
cost (\$)          number of bottles
x                                y
3. Using a piece of graph paper, plot the graph of number of bottles again cost (\$).
That is vertical axis - number of bottles
horizontal axis - cost (\$)
scale :   vertical axis - 2 cm - 1 unit
horizontal axis 1 cm - \$1
4. Record 3 observations that you obtained from the graph.

### Linear Graphs

Analyse the following diagram - what do they have in common?
Post your responses as a comment.

diagram 1

diagram 2

diagram 3

## Sunday, 28 July 2013

Key Questions

What are the characteristics of a gradient?
How is gradient connected to cartesian Coordinate?

Gradient (Slope) of a Straight Line

The Gradient (also called Slope) of a straight line shows how steep a straight line is.

Activity and self exploration

SUMMARY

### LINEAR GRAPH

SELF DIRECTED / COLLABORATIVE ACTIVITY

Watch the following video and have a better understanding of:
.1 Cartesian Plane
.2 Coordinate system and ordered pairs
.3 Plotting coordinates for both tabular and graphical forms.

This is a collaborative activity.

Using Linoit (click  post the key information about cartesian planes and coordinate system.

video 1

Video 2

LINOIT activity

### LINEAR GRAPHS - INTRO

INTRODUCTION

A visitor to SST from one of the GCP schools wanted to know the direction from SST to NLB @ Clementi.

Without using any GPS and technological based tools provide a concise direction to the venue.

Conditions:
He is travelling alone and plans to walk to the destination.

You direction should bring him to the doorstep.
Post your direction as a comment in this blog

With your group, brainstorm and suggesting a possible solution to the following scenario. Post your solution as a comment.

Scenario: You are lost at sea drifting aimlessly with water supply and a bar of magnet. Suggest how you could find direction to find land. What could be most useful a equipment for you to have at that moment, Why?

## Wednesday, 17 July 2013

### Level Test 2

posted Jul 16, 2013, 7:25 PM by Lim Ching Ching
 Date: 21 August 2013 (Wednesday) Duration: 1 hour Calculator is allowed. Topics that will be tested: 1. Basic Algebra and Algebraic Manipulation 2. Linear Equations & Simple Inequalities 3. Factorisation 4. Percentage 5. Functions & Linear Graphs (Pg 1-10) 6. Statistical Data Handling 7. Ratio, Rate & Speed

### Coverage for Term 3

1. Week 1-3 Statistics
2. Week 4    Ratio, rate & speed
3. Week 5-6 Functions & Linear Graphs
4. Week 7    Direct & inverse proportion
5. Week 8    Number sequences
6. Week 9    Basic Geometry & Polygons
7. Week 10  Geometrical Construction

### ACTIVITY: Stem and Leaf Diagram

Reference: Study Notes - Constructing a Stem-and-Leaf Diagram (p20)

Scenario:

Because of Singapore's geographical location, we are impacted by smoke haze when there are forest fires in the region and the prevailing southwest monsoon winds blow the smoke from the fires in our direction, which usually occur in the period of May to October.

However, Singapore experiences the worst haze situation in June this year.
We are going to analyse how different the quality of air in each zone, compared to the overall quality of air in Singapore.

(A) Gathering Data

1. Each team will be assigned to plot a stem-and-leaf diagram for the PSI value of and assigned zone (north, south, east, west), against the overall Singapore PSI value.

2. Retrieve the data from the NEA website:

3. Your reference time for everyday will be 8 am.
As the overall Singapore PSI value is presented in a range. Use the mid-point for the plotting.

(B) Organising and Presenting Data

4. The leaves on the left should be the data of the "Overall Singapore PSI value" whereas those on the right would be that of the 'zone' that your team has been assigned to.

5. Remember to include the "Key" to both sets of data.

(C) Analysing Data

6. Using the Stem-and-Leaf diagram, find the mean, median and mode of both sets of data.
Show the working to obtain the mean of each set of data clearly.

7. For each set of data, attempt to use the mean, median and mode to discuss the haze situation over the month.

8. Make a comparison of these 2 sets of data, and comment the haze situation at the zone (that your team has been assigned to) and the overall value.

Below is the chart that represents the number of hotspots in Sumatra (from 6 June to 5 July).

9. Make reference to the Overall Singapore PSI values for the month, what observations can you draw between Singapore's PSI value and the hotspots detected in Sumatra? Comment on your observations.

Submission:

1. Complete the task on the A3 size paper provided (during lesson).
Remember to include your Group Number, Team Number & Name of members of the team in the same page.
Criteria for assessment: Mathematically correct (concept and presentation) and aesthetic design

2. Put up your solution on the noticeboard at the back of the classroom by next Monday 15 July 2013 (Monday)

## Tuesday, 16 July 2013

### Mean, Median, Mode and Range

The meanmedian and mode are types of average.
The range gives a measure of the spread of a set of data.

This section revises how to calculate these measures for a simple set of data.
It then goes on to look at how the measures can be calculated for a table of data.

### Calculating the Mean, Median, Mode and Range for simple data

The table below shows how to calculate the mean, median, mode and range for two sets of data.
Set A contains the numbers 2, 2, 3, 5, 5, 7, 8 and
Set B contains the numbers 2, 3, 3, 4, 6, 7.

### Given a Table of values

Click here to find out now to find the mean, mode and median from this table.

### Activity 2

Complete the activity on 'he number of doors' to include mean, mode, median and range.

## Measures of Central Tendency or Averages

Arithmetic Mean
• The arithmetic mean of a set of numbers is the sum of numbers divided by the number of numbers in the set : Mean = sum of the numbers/number of numbers
• It is most the reliable measure provided there are no extreme values in the data because all the values in the data are used in calculating.
• Whenever the set of data contains extreme values, the median or mode would probably be more reliable because they are not influenced by extreme values.
Mode
• The number which occurs most frequently in a set of numbers
• It is most useful in business planning as a measure of popularity that reflects central tendency or opinion.
Median
• May be preferred as a measure of central tendency for describing economic, sociological and educational data.
• The median is popular in the study of social sciences because much of the data in the social sciences contain extreme values, in the set of household incomes.
• Median for an odd number of numbers is the middle number when the numbers are arranged in order of magnitude (i.e. ascending/descending order)
• Median for an even number of numbers is the mean of the two middle numbers when the numbers are arranged in order of magnitude
Listen to the following song for key concepts on Mean, Median or Mode.

Simple Activity
Go through the simple activity on Mean, Median, Mode and Range from this site.

## Thursday, 4 July 2013

### Data Type

1. Explain the difference(s) between the 2 diagrams.

2. What is the difference between discrete and continuous data?

3. What is the relationship between Histogram and continuous data?

## Tuesday, 2 July 2013

### Representation of Data - "Out-of-the-Box" way

source: LKY

The number of dengue infections has risen to an alarming number in 2013. NEA has been providing the public with updates, and at the same time sending alerts via the media to caution and educate the public.

Below is one of the ways that NEA presents information updates to the public:

Compare this "way" of presenting data with the "conventional" way of presenting data.

### Data Handling: Bar Graph vs Histogram - The Challenge

source: LKY

Ms Manju, the school librarian, makes use of the database management system to keep track of the loans by students.

Each month, she would present the data below in a bar graph. The bar graph shows the total number of books borrowed by category from January to May.

The Challenge
From the way the system captures the information, there are more useful information that can be extracted from the system for use.

Suggest to Ms Manju how she could make use of the data captured in the system to present a different set of information (other than the number of books borrowed by categories) using a histogram. Elaborate how this information can be used to work out with a strategy to encourage students to read more books.

As a group, present your suggested solution in the A3 paper provided. You may do 'mock up' on how the histogram looks like. Remember to label the axes of the histogram clearly.

Below the histogram, elaborate how this information can be used to work out a strategy to encourage students to read more books.

Submission:
Submit your answer to Ms Loh's pigeonhole upon completion (before Thursday 4 July 2013)
Remember to include your Class, Group number, Name of Group Members at the bottom of the paper.

### "Dengue" Data: Let's Compare and Find out "What's Wrong"

source: LKY

The number of dengue infections has risen to an alarming number in 2013. NEA has been providing the public with updates, and at the same time sending alerts via the media to caution and educate the public.

The line graphs below is one set of information that it has been updating the public.
Make a 'guess', what's the intent behind communicating this figures to the public?

Examine these two line graphs carefully.
While they "attempt"the report similar information, there's something not quite right in the way data is presented in one of the graphs.
Can you tell "What's Wrong" with which graph?

Source of Data: http://www.x-dengue.com/Home/Summary (correct as on 5 June 2013)