Labs are used to demonstrate principles and concepts that can not be easily communicated in any other way in the classroom. It is important for you, the student, to demonstrate that you understand the concepts learned in the lab. This can be done when you write up your lab report. This is the opportunity to show what you have learned in the class. The better the lab report the better (easier) it is to show your knowledge.

GENERAL INFORMATION FOR LAB WRITE-UP:

1. Single side of the paper
2. Written in ink
3. 1” margins
4. White paper
5. Stapled in the upper left corner
6. Name, date, period on the upper right corner
7. Each section must be clearly labeled
8. Spelling, grammar, and punctuation are to be error free
9. All graphs, charts, calculations, tables, etc. must have labels and correct units
10. All data presented must be clearly identified
11. All lines must be neat and straight

Your lab reports for this class should have the following parts:

TITLE: Use the same title as the lab instructions use.

INTRODUCTION: In your own words, tell what principles you are exploring in this lab. Make sure you state the purpose from the scientific point of view, not the educational point of view. (Don’t say “To learn…”). After the statement of purpose, include 3-4 sentences of background information. This should include principles, laws, theories, concepts, or other information that applies to the lab.

MATERIALS: Make a list of all materials used in the lab. This should include name and formula, i.e. Sodium Chloride (NaCl), size, quantity, etc.

PROCEDURE: In your own words, paragraph style, tell what you did in the lab. Make sure you tell what you actually did, even if the written directions said something different. Do not copy the directions. Include a moderate amount of detail, but do not go into the fine points of how you did something. This should be written in the passive voice and past tense. Any precautions, verbal instructions, and safety concerns should be listed at the end of the procedure section.

Good examples:   1. “Water was mixed with NaCl and sand. The solution was then poured through the filter paper.”

2. “After obtaining the sample, the cotton swab was wiped across the agar in the Petri dish, which was then incubated for two days.”

Bad examples:      1.  “Measure 100 ml of water in a graduated cylinder and place in a 250 ml beaker. Add 25 g of NaCl and 5 grams of sand and mix. Pour through the filter paper and allow to filter.”

1. “Obtain a cotton swab that has been rubbed on a surface. Wipe the swab across the top of the agar that is in the Petri dish. Place the dish in the incubator a t 30°C and incubate for 2 days.”

(These are too long, detailed, and are written in the present, 3^rd person.)

HYPOTHESIS: Write, in your own words, an IF/THEN statement predicting the outcome of each part of the lab. Example 1: If the sugar solution and the Benedicts is mixed and heated it will turn purple. Example 2: If the potato is tested with iodine, then it will test positive for starch.

DATA: This is the results of the lab – what happened. This section may include measurements or observations. Organize your results into one or more data tables. Use a ruler to make you data table. Make sure you record all original measurements as will as the results of any calculations you make. If you have calculations to do, show them after the data table. Show you calculation by writing the formula you will use, then substitute your values into the formula, and show your results, including units.

INTERPRETATIONS: Write an essay of 2-3 paragraphs in which you discuss and interpret the results. Explain how your data answers the question in the purpose of the lab. Discuss whether or not your data agrees with your hypothesis. Explain what was causing things to happen the way they did. Be sure to base your interpretations on  the results of the lab, not on the textbook.

If the lab includes numerical data, analyze it carefully. Look for patterns in the numbers. Often, it will be necessary to do some arithmetic in analyzing you data. A group of numbers representing several measurements of the same quantity should be averaged. If you are looking for a change or difference in a quantity, subtract the numbers. These results should be shown in you data table, along with your original measurements.

This is your chance to convince the teacher that you understand what the lab was about. The time to understand the lab is while you are working on it. It is too late to ask questions when you are at home doing the lab write-up. Discuss the lab and its conclusions with your partner and ask the teacher about anything you do not understand.

QUESTIONS: Include all the questions in the lab instruction in you discussion. You do not need to write out the question, but you need to incorporate the question in the answer as a complete sentence.

Example:  The question is: What was the best temperature to grow bean sprouts?

Poor answer: 20°C

Good answer: The best temperature to grow bean sprouts is 20°C.

CONCLUSION: This should be a short paragraph telling your teacher what you should have learned. You should explain the results of your lab. And the implication of your results in the real world, in paragraph form.

You can download the handout here: How to Write a Lab Report