Designing an experiment

Planning -

1.what is the objective or the aim?
2. Do I have an hypothesis that I will test - can I make up an hypothesis to test --For lots of details about making an hypothesis go here
3. Plan a method that will test your idea or hypothesis

Carry out the experiment

  1. remember to repeat the test a few times and average your results
  2. If your experiment is about behaviour / the brain or people you may need to repeat it at least 15 times -
  3. record the results in a table

Writing up the report

an excellent report will have at least the following
1. Title - this is a heading for your experiment- it is generally a few words that indicates what the experiment is broadly about; eg Water and plant growth, Bouncing Ball experiment

2. Background or introduction - a brief outline of the scientific concepts involved in the expt

3a. aim - This states what you are trying to achieve. Eg to determine the height from a which a ball is dropped determines the height of the bounce.

3b. Hypothesis -- Your best guess as to what might happen ; eg my hypothesis is that a ball dropped from 1 m will bounce higher than a ball dropped from 0.5 of a metre. The best hypotheses identify the dependent and independent variable and predict what happens as they interact.

4. method - with diagrams and steps to explain what to do in the experiment.
To write the method you need think about your aim and hypothesis and decide what steps you would take to carry out his activity. The steps will include how you will control other variables that you are not testing. You might also list the equipment or material you will need and also the safety steps required.

5. Results table that includes at least 3 trials for ...... results can also include
6. Discussion - and how you kept the variables constant and only tested the variables you wanted to test. You will also mention where errors may have crept into your method or prevented you collecting your results data. AND ways you might change your method to overcome the errors you have identified.

7. Conclusion -this will describe your findings and any relationship between any of the findings

Independent and dependent variables

Independent variable is the one the scientist changes IVC
Dependent variable is the one the scientist measures DVM
Controlled variable is the one s you make stay the same CVSTS

Lets apply this to the experiment that 2 students carried out where they burnt some different types of paper in order to find if thickness affects how quickly a paper burns.
IF the paper is thin THEN it will burn in a shorter time
IVC Independent Variable changed by the scientist )is the paper types
DVM (Dependent Variable Measured by the scientist) is the time it take sto burn
CVSTS (Controlled variable stays the same) - paper size , distance form flame

Here are some exercises in identifying the IVC and DVM etc and writing hypotheses

A more detailed outline

Question: What's a variable?
Answer: A variable is an height, temperature, time, feeling, pH, concentration, time period, or any other type of category you are trying to measure. There are two types of variables-independent and dependent.
Question: What is an independent variable?
Answer: An independent variable is not changed by the other things that are going on in an experiment. It is sometimes the thing you are trying to see how it affects the other variables. It is a variable that stands alone and isn't changed by the other variables you are trying to measure.
For example, someone's age might be an independent variable. Other factors (such as what they eat, how much they go to school, how much television they watch) aren't going to change a person's age. In fact, when you are looking for some kind of relationship between variables you are trying to see if the independent variable causes some kind of change in the other variables, or dependent variables.
Question: What's a dependent variable?
Answer: Dependent Variable:
A dependent variable is what you measure in the experiment and what is affected during the experiment. The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable. In a scientific experiment, you cannot have a dependent variable without an independent variable.
Example: You are interested in how stress affects heart rate in humans. Your independent variable would be the stress and the dependent variable would be the heart rate. You can directly manipulate stress levels in your human subjects and measure how those stress levels change heart rate.

Scientific experimental techniques and practices in science
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