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Drops on a Penny

Drops on a Penny. Attendance Equipment List Beaker, Pipette Variables Selecting your experiment Procedure Writing your procedure Upcoming: Tomorrow - Conducting your experiment. Equipment List. A new special section in your science binder

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Drops on a Penny

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  1. Drops on a Penny • Attendance • Equipment List • Beaker, Pipette • Variables • Selecting your experiment • Procedure • Writing your procedure • Upcoming: • Tomorrow - Conducting your experiment

  2. Equipment List • A new special section in your science binder • Will be continuously updated through the course.

  3. Extending Drops on a Penny • What variable would you like to explore when you re-do the drops on a penny experiment? • What one thing would you like to change?

  4. Some Other Variables • Person dropping the drops • Speed of drops • Height of dropper • Size of drops (Pressure on Pipette) • Type of Penny (side, year, country, old penny vs. new penny etc.) • Pipette used to drop the drops • Table location and sources of Vibration • Different types of soap (dish soap, hand soap, laundry soap, etc.

  5. Types of Variables • Independent (X-Axis) • It is the variable that YOU manipulate(change); it is the variable that is causing something to change (cause) • Dependent (Y-Axis) • It is a variable that you measure to determine any change (effect) • Control • The variables that you control so that you are making sure the experiment is “fair” to all tested materials

  6. Variables for Your Experiment • Dependent Variable • All of us will measure the number of drops • Independent Variable • What is your independent variable? • Control Variables • List at least 5 variables that you will not change

  7. Planning & Prediction • Question: • e.g. “How will a shiny penny affect the number of drops?” • Prediction & Hypothesis: • Use an IF… THEN… BECAUSE… format • e.g. “If the shininess of the penny increases then the number of drops will decrease. This is because a shiny penny has a more slippery surface.”

  8. Planning your experiment • Question: • E.g. “How will soap affect the number of drops?” • Prediction & Hypothesis: • E.g. “If soapy water is added to the penny, then the number of drops that can fit on a penny will decrease I think this will happen because...”

  9. Procedure • Write a procedure to test your hypothesis. • Step by step process for the experiment (past tense, passive voice) • Use the following format: • Use complete sentences • Should be written in numbered steps • steps that are common sense should be omitted (for example: “Goggles were used”; “The materials were gathered”). • Always use the past tense ( “A pipette was used…”) • Describe what you changed and measured • Describe how you kept other factors constant (controls) • Provide enough detail so that someone could repeat your experiment just using your procedure • Safety precautions and proper disposal of chemicals should be included in your procedure. E.g., • 10-cm long sheets of each paper towel brand were used. • 3-mL samples of 2% milk were placed on a wooden surface. • Once you show your procedure to your teacher, you may begin your experiment.

  10. Procedure-Example 1. A micro-well was filled half full with distilled water. 2. A small amount of sodium chloride was added to the water. 3. The mixture was stirred with a glass stirring rod. 4. The conductivity of the mixture was tested using the conductivity tester. 5. Steps 1-4 were repeated for all samples.

  11. Procedure-Example • 1: The same penny, same side, and same pipette was used throughout the experiment. • 2. The penny was rinsed with tap water and dried completely. • 3. The penny was placed on paper towel. • 4. A pipette was used to place drops of WATER on the head of the penny (one at a time) until the amount of water ran over the edge of the penny. • 5. The number of drops for the trial was recorded in the table. • 6. Steps 1 - 4 were repeated three more times before calculating the average.

  12. Data • Conduct at least 3 trials and find the average. • Also record qualitative observations

  13. Analyze the data and draw conclusions. • Write a paragraph below (using complete sentences) that explains how your independent variable affects the the number of drops that can fit on a penny , using your data to help you answer the question. Suggest a reason for your observations(Why did it happen). Support or reject your hypothesis. • You should also include any possible sources of error. This is especially important if anything went wrong during the execution of the lab, but should be addressed regardless of any known errors. Other questions you may address include: • Did you identify any possible improvements or changes if you were to do the lab again? • Did your lab or outcomes generate any additional questions to explore?

  14. Sources of error

  15. Systematic Errors- Penny Lab • Inaccurate counting • Improper cleaning of penny between trials • Different concentration of testing liquid on the penny (E.g., salt added to water not measured) • Size of the water droplets • Size of the eyedroppers

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