Experiment #1: Which toilet paper has the greatest strength when wet? Standard Procedure
Follow the instructions and record data in a notebook as described.
Introduction
This lab activity is designed to familiarize students with the strategies of the scientific method. This activity provides the opportunity to work through the steps as a scientist might when faced with such a question.
Question Which toilet paper has the greatest strength when wet? Some scientists work for consumer testing agencies to help evaluate the effectiveness of consumer products. Four brands of toilet paper (each brand signified by a different letter A, B, C, D) are provided for evaluation. All groups will perform the same standard procedure. This experiment is just one possible way to determine which brand of toilet paper is strongest when wet.
Chemical Concepts
Scientific Method
Independent/Dependent Variables
Materials needed (for each student group):
3 Toilet paper squares each of 4 different brands Water Rubber bands, 4 Pennies Beral-type pipet, 1 Graph paper Beaker, 100-mL
Observations Before making a hypothesis about which brand of toilet paper will be the strongest when wet, the four brands of toilet paper need to be examined. 1. Label a section in the notebook “Observations” 2. Get one square of each brand of toilet paper (A, B, C, D) and make as many observations as possible about the squares. 3. Observe the paper’s textures, thickness, fibers, etc… 4. Record these observations in the notebook.
Hypothesis 1. Based upon observations of the four brands, and avoiding pronouns such as I, we, us, etc., formulate a hypothesis about which toilet paper will have the greatest strength when wet. Example: Brand ____ toilet paper will be the strongest when wet because ______. 2. Write the hypothesis in the notebook. Procedure
1. Copy Table 1 from Data Presentation into the notebook. 2. Place one sheet of the first toilet paper brand (A) over the top of the beaker. Use the rubber band hold the toilet paper tight like a drumhead around the beaker. 3. Use a pipet to add exactly 3 drops of water to the center of the toilet paper. (Note: The key here is to be consistent by adding the same number of drops of water to the toilet paper sample each time.) Wait 10 seconds to allow the water to spread. 4. GENTLY place the pennies onto the center of the toilet paper, one at a time. Stop as soon as the paper breaks. Do not drop the pennies on the paper. 5. Count the pennies that fell into the beaker. Record this value in Table 1 in the notebook. Save the pennies for reuse. 6. Repeat this experiment two more times with the same toilet paper brand, recording all data in Table 1 in the notebook. 7. Repeat the Procedure (steps 1-6) for the three other toilet paper brands (B, C, D). 8. When data collection is complete, clean up your area. Organize all pennies and rubber bands as directed by the teacher. Discard used toilet paper samples.
Data Presentation
Table 1. Data Table Number of Pennies Applied Before Breaking Toilet Paper Trial 1 Trial 2 Trial 3 Average Paper A
Paper B
Paper C
Paper D
Data Analysis
1. Calculate the average number of pennies needed to rip through each sample of toilet paper and record these values in Table 1 in the notebook. Show the work calculations on the same page. 2. Use graph paper to construct a bar graph, plotting the independent variable (toilet paper brand) on the x- axis and the dependent variable (average number of pennies to break) on the y-axis. Use the average number of pennies (rather than plotting all three trials) and be sure to label the axes with the variables and units as needed.
Conclusion
1. Write a conclusion based on the data gathered from the experiment. Was the hypothesis supported or contradicted? The conclusion should take the form, “Based on the data, brand ____ toilet paper (did/did not) have the greatest strength when wet and, therefore, the hypothesis was (supported/contradicted).” 2. List 3 ways in which the procedure could be improved to give more reliable data. (Note: During any experiment, it is good practice to record if and where any errors or inconsistencies may have occurred and whether they are equipment related.) Each Student turns in a unique Lab Report: 1. Problem statement in your own words (Do not use I, me, we…) 2. Observations 3. Hypothesis 4. Data Presentation (Table) 5. Data Analysis (Calculations and Graph) Handwritten is acceptable. 6. 5 extra credit points for a computer generated graph! 7. Conclusions (Answer Questions in Complete Sentences) Example response for question #2: Three ways in which the procedure could be improved to give more reliable data are this, that, and the other thing.