# Experimental Design 2009-2010.

## Presentation on theme: "Experimental Design 2009-2010."— Presentation transcript:

Experimental Design

Description Teams must design, conduct and report the findings of an experiment conducted on site. 50 minutes Need to come up with the experiment quickly The event supervisor must assign a question/topic area that determines the focus of the experiment. Must have a relationship between independent and dependent variable.

Description Up to 3 team members Outline or Rubric will be provided
The more, the better in order to be able to complete all parts of the experiment/rubric. Outline or Rubric will be provided Examples Additional paper will also be provided May or may not include graph paper

Description All teams must be provided with the same materials.
List of materials will be provided. Card or list or list on board Kept secret until the start of the event Students must use at least two of the provided materials to design and conduct an experiment.

Items the students need to bring
Safety Goggles Chemical Writing instruments Timepiece Ruler Non-programmable calculator

Statement of Problem Not a yes/no answered question
Include independent and dependent variables Testable How does the length of the rubber band change when the metal washers are hung on it?

Hypothesis Must be a prediction between the independent and dependent variable Most often an if-then statement but not always Include a rationale for the hypothesis If the number of washers increases, then the length of the rubber band will also increase. In bungee jumping, the rope is stretched further if the person is heavier.

Variables Independent
The factor that is manipulated – you have control Operationally defined At least three levels The independent variable is the number of metal washers (3, 6 or 9) hung on the rubber band.

Variables Dependent The factor that responds to the Independent variable – you have no control Operationally defined The dependent variable is the length (in cm) that the rubber band stretches.

Variables Constants The items in the experiment that remain (or should remain ) the same throughout the experiment. Need at least 4 for the points!! Size of washers, mass of washers, size of rubber band, mass of rubber band, size of paper clip, mass of paper clip, the place where the rubber band was hung, the place on the paperclip where the washers were hung, the person measuring, the person adding the washers, etc.

Experimental Control (Standard of Comparison)
Standard to which the observed experimental effects are compared Object not being tested (see below) Drop heights – could be the shortest height or the highest height depending on the hypothesis Sometimes no control group but must be stated with rationale The experimental control is the rubber band being hung with no washers as this eliminates a variable. Therefore, we can compare the other data gathered to the control.

Materials Materials list must be separate from procedure
Only list materials used – be specific Use a list format Centimeter ruler 2 – 5 cm long paperclips 1 rubber band (4.8 cm long) Paper Pencil

Procedure Numbered steps in logical sequence Diagrams, if possible
Give enough information so that the judge could duplicate your experiment at home and get the same results Repeated trials

Procedure example Gather materials
Set up your paperclips and bend out the outer end (see diagram#1). Then slip the rubber band on to the inner edge and into the loop of another paperclip (diagram#1). Repeat step #3, three times and record data in data table. Find average Clean up area

Qualitative Observations
Using your senses, what is happening Need to have observations at the beginning, middle and end…throughout the experiment!! Observations may have nothing to do with experiment but you may need them later Summarize

Qualitative Observations
We noticed during the experiment that we may not have always measured the length of the rubber band accurately with the ruler. Someone’s rubber band broke and scared us. Someone opened the door.

Quantitative Observations – Data Table
Data Table with rows and columns labeled. Measurement labels included Average Calculation examples Division C only – Significant figures

Quantitative Observations – Data Table
Number of Washers Trial 1 Trial 2 Trial 3 Average 4.13 cm 4.18 cm 4.20 cm 4.17 cm 3 5.12 cm 5.16 cm 5.08 cm 6 6.20 cm 6.23 cm 6.26 cm 9 7.93 cm 8.02 cm 7.98 cm 7.976 cm

Graphs Graph independent variable on the x-axis and the dependent variable on the y-axis Title and axis headings Constant spacing in graph Graph appropriate for data Neat

Statistics Average Median, mode, range Division C only
Range of standard deviation Regression analysis (line of best fit) Other appropriate statistics

To Find Standard Deviation
Find the mean of the scores Subtract the mean from each individual score Square each of the differences obtained in Step #2 Add all of the squares obtained in Step #3 Divide the total from Step #4 b the total number of values minus 1 (n-1) Take the square root of Step #5

Analysis and Interpretation
All statements must be supported by data. Discuss any unusual data points and why Discuss trends and what they mean Discuss the statistics and what they mean Weakest area More than one sentence If nothing unusual, then say so Descriptive as possible

Analysis and Interpretation
When there were no washers on the rubber band, it stretched 4.13 cm in Trial 1, 4.18 cm in Trial 2, 4.20 cm in Trial 3, the average was 4.17 cm, the median was 4.18 cm there was no mode. Range is used for average the less the range the more accurate the experiment. It seems that all our trials were fairly accurate. It also seems that as more washers were added, rubber band stretches farther.

Possible Experimental Errors
Not only point out the errors that could have occurred but how the error might impact the data – BE SPECIFIC Human reaction time and other human errors Random vs Systemic errors

Possible Experimental Errors
One possible error in this experiment deals with the fact the human eye isn’t perfect, nor are we, and it is likely that when reading the ruler, we might decide on a measurement that is slightly high or slightly low. This changing of the variable pieces may or may not have affected our data, but after completing the experiment we realized that it might have been a mistake on our part not to have evenly distributed the washers before each and every trial

Conclusion Restate the hypothesis
State reasons whether the results support or refute your hypothesis You never prove anything Explain how the data impacts your hypothesis If you refute your hypothesis, then propose a new one.

Conclusion The purpose of this experiment is to test how the mass of the washers affect the length of a rubber band. Our hypothesis was, “If the number of washers increases, then the length of the rubber band will also increase. This hypothesis was supported because the average length of the rubber band with 0 washers was 4.17 cm… This data shows a steady increase in the rubber band’s length as the number of washers weighing down on it increases. However, further experimentation is needed for accurate results.

Applications and Recommendations
Give suggestions for the improvement of this experiment Give suggestions for other ways to test your hypothesis Give suggestions for future experiments that would help to understand the statement of problem better. Practical applications.

Applications and Recommendations
One recommendation for future attempts at this experiment would be to choose a device that holds the washers in the exact same position every time, unlike our bent paperclips which allowed for some movement. Use a camera for more accurate measurements. Dumb bells and exercise bands Bungee jumping – Practical application

Scoring See rubric Tie breakers Safety Procedures – DQ
Variables Procedure Analysis of results Graphs Data Table Most points Safety Procedures – DQ Not addressing the assigned question – ranked below those that did

Thoughts Brainstorm for only 5 minutes Divide the tasks
50 minutes total for the competition Make task vague and specific Divide the tasks Everyone must write Only 50 minutes total for the competition

Thoughts Ask to tear the pages apart
Could lose points if not permitted or not put back together in the proper order Make sure all sections are labeled with letter and title Practice, score and keep all experiments Good Review for competition Shows growth and problem areas

Thoughts Train with alternates Practice with lots or little equipment
Never know competition schedule or flu schedule Practice with lots or little equipment Same experiment

Examples Devise and carry out an investigation to show the relationship between volume and mass is linear. Your experiment must deal with one of the variables of a pendulum to identify the effect it has on the period of the pendulum. In honor of Sir Isaac Newton, your experiment must involve dropping objects. Today’s experiment must involve friction.

Examples Using the following materials, conduct an experiment relating to some aspect of CONSTRUCTION. Show a relationship between the mechanical advantage of a lever and its efficiency. Your experiment must use the paper towel, napkin and brown paper towel in some manner.

Your Task Design an airplane experiment using the newspaper, ditto paper and construction paper. Materials Three types of paper (8.5 in by 11 in) Measuring tape (Shared) Ruler Paper clips (3 per group)