In a lab report, confounding factors should be discussed in the "Methods" or "Materials and Methods" section. This is where you should describe the procedures and methods used in the experiment, including any potential sources of bias or confounding that may have influenced the results.

You should clearly identify and describe any factors that may have affected the outcome of the experiment, and explain how you controlled for them. This may include things like environmental factors, subject characteristics, or other variables that could have impacted the results.

It's important to acknowledge and address potential confounding factors in your lab report in order to ensure that your results are accurate and reliable. By identifying and controlling for potential sources of bias or error, you can increase the validity of your experiment and help ensure that your findings are trustworthy.