In the first episode of really and truly talking about experimental design, I talk about the Fourth Edition Task List item B-03: Systematically arrange independent variables to demonstrate their effects on dependent variables. More specifically, I get into extraneous and confounding variables, plus threats to internal validity (#FUNAF). 
References: 
Cooper, J. O., Heron, T. E., & Heward, W. L. (2020). Applied behavior analysis (3rd ed.). Upper Saddle River, NJ: Prentice Hall.
Ledford, J. R. & Gast, D. L. (2018). Single case research methodology: Applications in special education and behavioral sciences (3rd ed.). New York, NY: Routledge.
If you're looking for additional information on everything we talked about, you can find it here:
Independent variables - Cooper, pg. 156
Dependent variables - Cooper, pg. 156
Extraneous variables - Cooper, pg. 160
Confounding variables - Cooper, pg. 226-230
Threats to internal validity - Ledford & Gast, pg. 19-23
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