Science: Writing a Formal Lab Report
Organizing evidence, analysis, and conclusions in scientific writing
Science: Writing a Formal Lab Report
Organizing evidence, analysis, and conclusions in scientific writing
Science - Grade 9-12
- 1
List the major sections that are usually included in a formal lab report in the order they should appear.
Think about the order from introducing the experiment to explaining what the results mean.
A formal lab report usually includes a title, abstract or summary if required, introduction or purpose, hypothesis, materials, procedure, data or results, analysis or discussion, conclusion, sources of error, and references if outside sources are used. - 2
A student titles a lab report "Plant Lab." Rewrite this as a more specific and formal title for an experiment testing how different amounts of light affect bean plant growth.
A stronger formal title is "The Effect of Light Exposure on Bean Plant Growth." This title identifies both the independent variable and the dependent variable. - 3
Identify the independent variable, dependent variable, and one controlled variable in this experiment: Students test how water temperature affects the time needed for sugar to dissolve.
The independent variable is what the experimenter changes on purpose.
The independent variable is the water temperature. The dependent variable is the time needed for the sugar to dissolve. One controlled variable could be the amount of sugar, the volume of water, or the way the mixture is stirred. - 4
Write a testable hypothesis for this question: How does the concentration of saltwater affect the germination rate of radish seeds?
Use an if-then-because structure.
A testable hypothesis is: If the concentration of saltwater increases, then the germination rate of radish seeds will decrease because high salt levels can make it harder for seeds to absorb water. - 5
A student writes this purpose statement: "We did a lab to see stuff happen." Rewrite it as a formal purpose statement for a lab that measures how ramp height affects the speed of a toy car.
A formal purpose statement is: The purpose of this investigation was to determine how ramp height affects the speed of a toy car. - 6
Explain why the procedure section of a lab report should be written clearly enough for another student to repeat the experiment.
Connect clear procedures to repeatability and reliability.
The procedure must be clear and detailed so another student can repeat the experiment under the same conditions. This supports reliability because repeated trials can show whether the results are consistent. - 7
Improve this procedure step so it is more precise: "Heat the liquid for a while."
A more precise step is: Heat 50 mL of the liquid on a hot plate set to medium until it reaches 60 degrees Celsius, then maintain that temperature for 3 minutes. - 8
A data table for a reaction-rate lab has columns labeled "Trial," "Temperature," and "Time." Explain what important detail is missing from at least two column headings.
Scientific data must include measurement units.
The table is missing units. The headings should include details such as Temperature in degrees Celsius and Time in seconds so the measurements are clear and meaningful. - 9
Write a formal results sentence using this data: At 20 degrees Celsius, the average reaction time was 48 seconds. At 40 degrees Celsius, the average reaction time was 25 seconds.
The results showed that increasing the temperature from 20 degrees Celsius to 40 degrees Celsius decreased the average reaction time from 48 seconds to 25 seconds. - 10
A graph shows plant height over 4 weeks for plants given 0 mL, 50 mL, and 100 mL of water per day. State what should be placed on the x-axis and y-axis.
The independent variable usually goes on the x-axis, and the dependent variable usually goes on the y-axis.
The x-axis should show time in weeks because time is the independent variable for tracking growth. The y-axis should show plant height with units, such as centimeters, because plant height is the dependent variable. - 11
Describe the difference between the results section and the conclusion section of a formal lab report.
One section reports what happened, and the other explains what it means.
The results section presents the data, observations, tables, and graphs without extended interpretation. The conclusion section explains what the data means, states whether the hypothesis was supported, and connects the evidence to the scientific question. - 12
A student concludes, "My hypothesis was right because the experiment worked." Rewrite this as a stronger scientific conclusion using evidence from this result: Plants receiving 100 mL of water per day grew an average of 12 cm, while plants receiving 25 mL per day grew an average of 5 cm.
The hypothesis was supported because the plants that received 100 mL of water per day grew an average of 12 cm, while the plants that received 25 mL per day grew an average of only 5 cm. This evidence suggests that greater water availability increased plant growth under the conditions tested. - 13
Identify two possible sources of error in a lab that measures the effect of fertilizer amount on plant growth, and explain how each could affect the results.
Look for factors that could change the dependent variable besides the independent variable.
One possible source of error is uneven sunlight, which could cause some plants to grow more because of light rather than fertilizer. Another possible source of error is inaccurate fertilizer measurement, which could make the relationship between fertilizer amount and growth less reliable. - 14
Rewrite this sentence in a more formal scientific style: "I think the hot water made the tablet fizz way faster."
A more formal sentence is: The tablet reacted more quickly in hot water, as shown by the shorter time required for fizzing to stop. - 15
Review this mini data display: Trial 1 was 10.2 g, Trial 2 was 10.4 g, Trial 3 was 10.3 g. Calculate the average mass and write one sentence that could appear in the analysis section.
Add the three values and divide by the number of trials.
The average mass is 10.3 g because 10.2 g plus 10.4 g plus 10.3 g equals 30.9 g, and 30.9 g divided by 3 equals 10.3 g. An analysis sentence could be: The three trials produced a consistent average mass of 10.3 g, indicating that the measurements were precise.