Lab Report Guide - WhippleHill

Lab Report Guide - WhippleHill

Ms. Harrison’s

Guide to Great

Lab Reports

Habits of Mind

Think sdrawkcaB . . .

One strategy for writing good lab reports is backwards thinking. You should

always begin with the end in mind. Before you do your research, grab some test tubes,

frizz your hair in your best mad scientist look and get started, you need to stop and think

about what you need to accomplish. If you are reading this before designing and

carrying out your experiment, then you should pat yourself on your front and

congratulate yourself on thinking backwards.

O.K., now you’re feeling backwards, your shirts’ tag is itching your chin and it’s

time to start at the end . . . what do you do? Begin with two questions – what do I need to

accomplish, and what are my constraints. Make lists based on what you know.


• Find out how temperature affects

the speed at which black-­‐eyed

peas germinate.

• Collect data that I can graph.

• Identify a single dependent and

independent variable.


• I only have 2 weeks to complete

the experiment.

• I can only use black-­‐eyed peas

• I have to control the temperature

of the seeds using a heat lamp in

the classroom.

• I have to set up my experiment

with a control.

Your lists will be different from the ones above, but you should have your goals in mind

before you start and you must take into account your constraints. Once you know where

you are going, you can figure out the best way to get there without wasting precious time.

Be a control freak . . .

Being a control freak is just as important as thinking backwards. You should

design an experiment where you are in control of everything. You even need to be in

control of the control, more on that later. If you don’t control every aspect of your

experiment, then you risk having more than one independent variable in your

experiment. Remember, variable refers to something that changes and in a good science

experiment you only want to change one thing! For example, if you have two pea plants

that get different amounts of water and different amounts of sunlight – how will you

know which variable (sunlight or water) caused any changes you might measure? You

won’t know because you failed to control your pea, and scientists who can’t control their

pea may find themselves referred to as an incompetent incontinent. Try saying that

three times fast and then remind yourself in a good experiment – you change only one

thing at a time (independent variable) and you measure the affect of that change

(dependent variable(s)). It is o.k. to have more than one dependent variable, but not

more than one independent variable. For example, increasing hours of daylight

(independent variable) may cause pea plants to be taller (dependent variable), produce

more pea pods (dependent variable), and have thicker roots (dependent variable). All

other variables should be controlled. Here is a quick reference for thought . . .

Type of Variable Question it Answers Examples



“What do I change?” Amount of sunlight a plant




“What do I observe?” Height of plant, width of

roots, number of pea pods.

Controlled variable “What do I keep the


Amount of water the

plants receive, the type of

soil they are in, brand of

pea plant, etc, etc, etc, etc,


Thinking this way should help you control your control. A controlled experiment is an

experiment where ALL variables are controlled (kept the same), and you don’t change

anything (no independent variable).

Success is only the beginning

While coming to a conclusion (answering your question) may seem like an end to

you, for science it is part of a continually evolving process. Once you have reached an

answer, it is up to others to try and confirm or refute your answer. Science goes on and

on, always testing and considering, looking for new information or rethinking old –

never satisfied. Every answer is only one experiment away from being proven wrong

and being replaced with a new answer.

The Lab Report

General Items


This is just as you would expect, a reflection of the appearance and organization of your

work. Is it clearly presented? Remember, the care and effort you put into your report

reflect upon your character and will influence how people perceive you. While neatly

hand-­‐written reports with graphs on graph paper are acceptable, typed reports with

computer-­‐generated graphs are better. Ultimately, there are two important pieces

here . . .

1. Is your lab well organized – is the information located in the right place?

2. Is your information clear -­‐ is your grammar correct? Did you include graphs

that have labels? Are you graphs to scale? Did you include units?

Participation (not included in lab report)

Showing up and kindly staring while your group members do all the work is not

acceptable. You are expected to be on task at all times and to be helpful to your team

members. While participation is not a section to be included in your lab report, it is here

to remind you that it will be reflected in your lab grade.

The Lab Report Components


Before you try and write your question, make sure you have identified the independent

and dependent variables. Both what you will change and what you expect to observe

should be included in the question. The one thing that should not be in the question is



(right) Does the amount of light a pea plant receives affect the height of the plant?

(wrong) If I change the amount of light a pea plant receives, will it affect the height of

the plant?

The question is similar to putting a “Title” on your report. By using the question, you are

essentially giving your report a highly informative title.

Experimental Hypothesis

This is your best guess and it should make sense to you. Your hypothesis is your

prediction and should be followed by an explanation of why you think this will happen.

You can continue to use the IF . . . THEN . . . statement if you would like, just make sure

you use it correctly and follow it with an explanation of why you think it will happen.

AGAIN, avoid including you or I. Here is the correct way to do an IF . . . THEN . . .


IF (independent variable) THEN (dependent variable) and WHY

IF (what you change) THEN (what you predict you will observe) and WHY


If the amount of sunlight a pea plant receives is increased, then the pea plant will grow

higher. This is because the sunlight will give the pea plant energy to grow.

Truly, this is not a necessary step for scientific research – your hypothesis has no affect

on your results in the best-­‐case scenario and may cause you to be biased in the worst.

However, this step is very useful for students because it causes them to think about the

end of the experiment (backward design) and to focus their thoughts. It also forces you

to identify your variables, which is another important thing to know before you start. If

your prediction is incorrect, it will not cause you to lose any points or make your

experiment any less useful.


The key to this section is to include all necessary materials and to do so

quantitatively. Quantitative descriptions include amounts, measurements, brands, etc.

This section should be like a grocery list for a recipe that you expect someone to follow:


1. Gummy Bears

2. Beakers

3. Yard Stick

4. Water


1. 30 Brach’s Gummy Bears

2. 18 Beakers (100 ml)

3. Meter Stick

4. 1 Liter Distilled Water


The key to this section is to include all necessary steps and to do so in the proper

order of events. Similar to a recipe, this section is the instructions necessary for

someone other than yourself to re-­‐create your experiment. It is often a good idea to

have someone unfamiliar with your experiment to read your procedures. Often,

scientists will become so familiar with the process that they have a hard time explaining

it well to others. If your experiment has to be set-­‐up, it is useful to include pictures or

diagrams of your lab set-­‐up. Avoid “gather materials” or “clean up.” Only steps that

directly impact the results of the experiment should be listed.


This is where you share the data that you collected. This is NOT where you tell a reader

what you think the data means. A good result section should be clearly organized and

you should present your data in a way that is easy to interpret. Much of the time, this is

done by using graphs, tables, or pictures. Graphs are an easy way for our minds to

summarize data. Tables allow us to easily find the data we want amongst a large amount

of data. Pictures can also be useful and give the reader additional information.

Your results should be very accurate and easy to interpret. This is easily

accomplished when you use a computer to produce the tables or graphs of your data. If

you are not using a computer, all your graphs should be drawn to scale using graph

paper. Remember to label your data clearly.


This is where you say what you think the data tells you. You should always discuss the

relationship between your independent variable and dependent variable(s). Look for

trends in the data (ex. As sunlight increases, plant size increases). Look for problems

with the data and discuss why you think they might have occurred (ex. One of my plants

showed sign of disease and that may have contributed to it not fitting the data trend).

Discuss any new experiments that might be useful based on the data you collected or

ways that your experiment could be improved to collect better data. If there is no trend,

say so.

Conclusion – Part 1 (Hypothesis)

State whether your data supported or failed to support your hypothesis. You should

summarize how your data supported or failed to support your hypothesis.

Ex. Increasing the amount of sunlight a pea plant receives did increase the height of the

pea plant. The data showed a range of 8 cm for plants receiving 4 hours of sunlight to 17

cm for plants receiving 10 hours of sunlight. Although the hypothesis was supported,

the data showed greater increases in height between 4 hours of sunlight and 7 hours of


Conclusion – Part 2 (errors / improvements)

What kinds of errors could your lab include? Think about your measurements, the

amount of data collected, how it was collected, the materials you used, and any problems

you observed. Was the procedure followed precisely? How could you have set up your

experiment differently that might produce better results? If you were to repeat this

experiment, what would you change and why?

Conclusion – Part 3 (What was learned)

This quick summary should restate what was learned from the experiment. This should

be the “answer” to your original question. You should include your independent variable

and dependent variable(s). If the data does not support a conclusion, do not be afraid to

say that you were unable to make a conclusion.


From this experiment I learned that increasing the amount of sunlight a pea plant

receives does increase the height of the pea plant.


Because most of the pea plants I grew did not produce seedpods during the two-­‐week

period I observed them, I was unable to learn if the amount of sunlight a pea plant

receives affects the number of seedpods it produces.

Optional Sections

Background Sources (If Required)

If requested, please site any text (hard text & online) you use for information. Use

standard APA format.

Experimental Design (If Required)

This section is for experiments where you design the entire experiment. To receive full

credit, an experiment must be designed to test your Question. It may only have one

independent variable. It must have at least one measurable dependent variable. All

other variables must be controlled or accounted for.

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