Scientific Method Step 6: ConclusionsComplete Conclusions Include:- Was the hypothesis correct or incorrect? Be sure

to explain how it was or wasn’t?- Recap the results from your experiment.- Use your results to explain what happened in

your experiment and support it using scientific principles/terminology

- NOTE: If the hypothesis is incorrect, this leads to a new question and the scientific method starts again.

Which Conclusion is Complete? The hypothesis was incorrect. Next time, 3

trials should be conducted for each person to determine how much gum can fit in their mouth.

The hypothesis was correct, as it was found that 300 mL of water did achieve the greatest increase in growth with an average of 0.2 cm a month. Less water causes wilting and slower growth, while too much water causes the cells of the plant to burst.

Try it on your own on page 28-29

Scientific Method Step 7: Sources of Error and Improvements

Using the scientific method, we design experiments and try to obtain results that prove or disprove our hypothesis.

However, experiments are never flawless and scientists know that their results always contain errors.

Your goal when designing and performing your experiments is to minimize errors and to be aware of what errors may be present in your experiments.

You should also consider these errors when making your conclusions. Since all results contain errors, scientists

almost never give definite answers.  They are far more likely to say: "it is likely that ..." or "it is probable that ..." when making conclusions.

Sources of Error1. Random Errors (Errors beyond your control): These

errors occur because it is impossible to be 100% precise when taking measurements. You have little or no control over these errors. 

Examples:

• you can only be so accurate when reading a ruler or graduated cylinder

• the temperature and wind currents in the classroom will vary depending on the time of day and number of students present

How to reduce the effect of random errors: take an average of a number of trials

2. Planning Errors: These are errors caused by the way the experiment was designed and conducted.

Examples:

• The instrument/equipment you are using is not working correctly (ie. a voltmeter reads 1V even when not hooked up to a source, a scale is not properly tared and reads 0.05g when it should be at 0g)

• A tape measure has been stretched from years of use and no longer gives an accurate measurement

How to reduce the effect of planning errors: Planning errors cannot be eliminated by doing multiple trials but can be eliminated by changing your procedure or the way you perform the experiment.

Human Errors/Procedural Errors:

• Human errors usually result from making a mistake. 

• Spilling part of a solution, dropping part of a solid from the weighing paper, or doing a calculation wrong is a mistake, not a source of error. 

• They can be avoided by being careful. 

• If they do happen, an experimenter would start that trial over again and not include mistakes in their data.

The following examples are mistakes that should NOT have happened and they should NOT be part of your Sources of Error:

• spilling, or sloppiness, dropping the equipment, etc.

• bad calculations, doing math incorrectly, or using the wrong formula

• reading a measuring device incorrectly (thermometer, balance, etc.)

• not cleaning the equipment

• using the wrong chemical

• not following the planned procedure or being unprepared

Improvements:• After completing an experiment, scientists always review their

results and evaluate how effective their experiment was. They look for ways to improve their design and procedure to obtain more accurate results.

• As you are performing your experiments, you too should be thinking about how you could improve your experiments to minimize errors and maximize accuracy.

 

 

• Note: Your improvements should not be the same as your sources of error. You should be thinking of a variety of errors and improvements and not just rewriting an error as an improvement or vice versa.

RESULTS

Quantitative Information – measurements and numerical information

Qualitative Information– observed using senses

Observe what happens when you put water on a coin.

What happens when ……..…..?

    

How would I measure

…………..?

observationobservation

observationobservation

Observe what happens when you put water on a coin.

Choose one of your observations that is measurable.

This will be the DV.

THE DV IS:

Observe what happens when you put water on a coin. Step 2: Brainstorm

List any variables that could affect your DV (chosen in the starburst)

VARIABLES AFFECTING THE DV:

 

Observe what happens when you put water on a coin.

Choose one of your variables from your list.

This will be the IV. The rest of your list will need to be controlled and are the CVs.

Step 3: Fishbone: Experiment Organizer

CV

CV

CV

DV

CV

I

I

TU

TU

IV