Question

Activity 4: Experiment (YOU PRETEND TO DO THIS EXPERIMENT)

The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. A control group is used in an experiment as a point of comparison, so that it can be isolated in testing that the experiment did, or did not, have the intended effect.

For example, scientists have developed many tests using reagents (substances used to detect another substance) to identify the different biomolecules. In order to perform these tests correctly, two different treatments must be completed to provide standards for comparison. The first treatment is called a positive control and contains the variable being tested for. The second treatment is the negative control, which does not contain the variable being tested for. To make sure your testing chemicals are not contaminated and to see what a negative reaction to the test will look like.

• Exercise 3: Identify the parts of the experiment.   A researcher wants to find out if spraying fruits and vegetables with pesticides affects the vitamin levels in those foods.

     a) the independent variable: _______________________________________

     b) the dependent variable: _____________________________________

     c) two possible controlled variables: ________________________________

     d) the control group:   ___________________________________________

     e) the experimental group: __________________________________________

Activity 5: Data

Data are reported in objective terms that allow for independent interpretation by anyone reading the report. The preferred method of reporting data is the presentation of results in tables and graphs that provide a quick and clear overview of any observed effects. There are two types of data: qualitative and quantitative.    

Qulitative data include qualities such as color, smell and taste. These are subjectively perceived and can be difficult to express in an objective manner. While everyone conducting the experiment may agree that the solution changed color, there may be variation in what individuals identify as blue, light blue, etc.

Quntitative data include qualities that can be measured objectively such as weight, volume, length and temperature. Quantitative data have a number associated with them and can be reported in universally accepted measurable units. This makes it easy for others to interpret the results. Both types of data are valid and important. In some instances an experiment may result in just one or the other type of information. Frequently, the investigator may collect and report both types of data.

Exercise 4: Label the following as qualitative (L) or quantitative (N).

Temperature of 23 °C _____

Increase in color intensity _____

pH values _____

Bitter taste _____

Sound increase _____

Measurement of nitrates _____

Number of deaths _____

Precipitation _____

Sweet smell _____

Level of diversity _____

Activity 6: Results/Analysis

To understand data better, it is usually shown in some type of graphical format. The same data can be portrayed in different formats depending upon what is being emphasized. A pie chart shows the proportions of different categories (qualitative data). The amount of the pie (circle) correlates to the percentage. It can be as simple as just two categories or it can contain several categories. The more categories a chart has the more difficult it is to read. If there are many categories that have small numbers they are frequently lumped into an “Other” category.

Exercise 5a:   Creating a complex pie chart. Create a pie chart for a characteristic with at least four categories but not more than six. Choose a characteristic that varies among students. Appropriate examples include shoe type, color of pants, mobile phone service, or type of car owned. Each student should pick a different characteristic. To make data collection easy and fun, one by one students should introduce themselves to the entire class and the rest of the class can ask them about the characteristic they chose. Fill in the chart below and create a pie chart with your data.  

Characteristic _______________________

Category	Number of Students	Percent of Students

Answer 1

3 a) the independent variable: Pesticide

b) the dependent variable: Vitamin levels

c) two possible controlled variables: Amount of pesticide sprayed and the duration of pesticide on apple

d) the control group: Apple with no pesticide sprayed

e) the experimental group: Apple with pesticides sprayed

4 Temperature of 23 °C - Quantitative (N)

Increase in color intensity - Qualitative (L)

pH values - Quantitative (N)

Bitter taste - Qualitative (L)

Sound increase - Qualitative (L)

Measurement of nitrates - Quantitative (N)

Number of deaths - Quantitative (N)

Precipitation - Quantitative (N)

Sweet smell - Qualitative (L)

Level of diversity -  Quantitative (N)

6. Characteristic choosed  type of car owned.

Category	Number of students	Percentage of students
Hatchback	150	10.41
SUV	350	24.30
Crossover	400	27.77
Coupe	340	23.61
Sedan	200	13.88

Total number of students = 1440

Calculation of angle = (Number of students/Total number of students) × 360°

Hatchback (150/1440) x 360° = 38°

SUV (350/1440) x 360° = 88°

Crossover (400/1440) x 360° = 100°

Coupe (340/1440) x 360° = 85°

Sedan (200/1440) x 360° = 50°

To construct a pie chart

Locate a point, draw a circle with a convenient radius from the point. Mark a horizontal radius of this circle at any point. Start sectioning with the central angle of 38°, 88°, 100°, 85° and 50° respectively and shade them.