Crash Course on Lab Write-ups

1. Crash Course on Lab Write-ups

2. FORMAT • All lab reports are to follow this format: (make sure the content after the (:) is block justified. • Title: • Problem/Research ?: • Hypothesis: • Theory: • Variables: • Materials: • Methods: • Data: • Data Analysis: • Diagrams: • Conclusion & Evaluation:

3. TITLE • Descriptive: Use active verbs Examples: Not Good • Ascorbic Acid vs. Juices • Ascorbic Acid in different types of Juices • The Investigation of Ascorbic Acid in Differing Types of Juices Good • The Investigation of Ascorbic Acid Concentration in Differing Types of Fruit Juices

4. PROBLEM / RESEARCH ? • Use the title and continue the active verb • Include the variable tested • Your problem has to be testable • Should not have a yes or no answer Example: In this experiment we will investigate the amount of vitamin C (ascorbic acid) in different fruit juices by titration of the juice with a solution of DCIP. AA. is an important compound b/c… Humans cannot manufacture…. Therefore they must ingest… To make an informed decision…We ask the quest. “Does a citrus based juice contain more or less vitamin C than a non citrus based juice?” Bad: “Does a citrus juice contain better vitamin C than a non citrus based juice?” “Will drinking orange juice be better for you than drinking apple juice?

5. HYPOTHESIS • If…(assumption), then when we… (method), we will see (expected outcome), because (background knowledge) Example: • If higher amounts of AA are found in citrus drinks vs non citrus drinks, then when we titrate orange juice and apple juice, we will see it takes less drops of orange juice to neutralize DCIP because…. • If enzyme activity is related to temperature (or pH or quantity), then when we increase the temperature we will see an increase in the products of an enzymatic reaction because… • If diffusion efficiency is related to the ratio of surface area to volume, then when we decrease the SA/V (increasing volume of a cell mass), we will see a decrease in the rate of diffusion into a cellular mass (potato) because...

6. THEORY • Background research • Write what you know

7. VARIABLES • Dependent variable: what will change b/c of IV • Independent variable: the factor you control and change • Control Variables: what stays constant so they have no effect on the experiment • Experimental Control “standard of comparison” • IN YOUR LAB REPORT: Use the same color print for each of the variables in your lab and then list the variables in black.

8. MATERIALS • Numbered list • Indicate amounts: Some problems: • 0.25mg/l of DCIP • Orange juice • 10ml graduated cylinders • 5 beakers

9. METHODS • You should be able to hand it to mom and dad and they should be able to do exactly what you did • Always include…”repeat experiment with X# trials” • Include diagrams regarding the procedures Some problems with Vitamin C lab: -swirl -count # drops of ___ and record in data table -wait 30 sec -clean … contamin.

10. DATA • Descriptive titles • Appropriate units • Descriptive headings for variables Some problems: • # of drops • Sig figs • Not neat – use a ruler!

11. DATA ANALYSIS • Graphs • Descriptive title • Units and labels axis • key • Add a brief description of what the graph is about (think of a caption in the textbook) • Calculations • Calculated errors

12. CONCLUSION AND EVALUATION • This is an area which gives many students trouble. It requires looking at  the experimental title, the purpose, the data and calculation sections of the  lab report and bringing them all together. Sometimes it involves the comparison of the student's experimentally derived answer to a known literature value. A. Use your data (#’s) to explain whether your results support your hypothesis. Discuss trends. B. Start with the evaluation of your procedure. Systemic errors: Random errors: C. Discuss improvements