I’m looking for information regarding student comprehension and/or performance when given basic, succinct instructions versus long, detailed lab instructions. I have heard convincing arguments for both, but I’d like to find out what the research says.
—Brandi, Oklahoma City, Oklahoma

Following directions is highly valued skill in many classes. I once heard a teacher say to a lab group whose results were different from the others, “You got the wrong answer because you didn’t follow my directions.” He missed a teachable moment to discuss how or why different results were obtained.
Your question implies that knowing how to design procedures for lab investigations also would be a skill worth developing. I’m not familiar with any formal research on the complexity of lab directions, so I’m hoping someone who knows of any will share the references. In the meantime, this sounds like an opportunity for your own action research in the classroom.
Action research is inquiry or research focused on efforts to improve student learning. Typically it is designed and conducted by teachers or teams of teachers who analyze the data from their own classrooms to improve their practice. Action research gives teachers opportunities to reflect on their teaching, explore and test new strategies, assess the effectiveness of the new strategies, and make decisions about which ones to use. Action research models generally have several components, which I’ve annotated with some thoughts:

Identify a focus area or research question. You already have a general idea (the effectiveness of lab directions) to reflect on. What do you want your students to learn from lab activities? What did you observe that prompted your question? A detailed set of directions (often called a “cookbook” lab) would seem to be foolproof: students who follow the directions would be more likely to get the “correct” results. How important is it for all students to get the same results and come to the same conclusions? What happens if they do not? Depending on the amount of directions, how would you expect the students’ thought processes to be different? Once students are familiar with a procedure or instrument, is it necessary to repeat the directions? What is the teacher’s role if the directions are not detailed? Do students think a long, detailed set of directions looks more rigorous and scientific?

Collect data. If you have more than one section, you could use detailed directions in one class and basic ones in another. You may need to try this with several activities. You’ll need to document the impact of providing different amounts of directions: the accuracy or consistency of data students collected during the activity, how students analyzed their results, the content and quality of the discussions between members of the lab group, and the procedures designed by the students. As the students proceed, listen to their conversations. Ask questions about their understanding of the purpose of the activity and how they decided on a procedure. Observe which students become frustrated with the minimal directions or which students display confidence and creativity. You could use photographs or videos to document the process. Examine what they are writing in their lab notebooks.
Analyze and interpret the data. Review the students’ procedures and their results using a rubric based on your vision of what a successful lab “looks like.” Look at the quality of their reports. Debrief them on their understanding of the procedures they designed and of the results. Discuss any frustrations or other feelings about the change in expectations.
Develop an action plan. Depending on your results and the experience level of your students, you may decide that some modeling and scaffolding will be necessary as they take on more responsibility for their work. Decide if it is acceptable for students to design the procedure as they go along or whether you want them to outline a procedure before they start the hands-on work. Consider if there are times when detailed directions would be appropriate (perhaps if you’re introducing a new lab technique or new instrumentation, if there are safety concerns, or if your students are novices at organizing data). If implementing your action plan leads to more questions, the action research cycle continues.
Action research is a systematic way to apply inquiry to your own teaching practices, and in many schools it is used as a professional development option. The results of action research are often published in the NSTA journals. You can examine these articles for ideas. I hope you will share your findings with us!
Resources:
Action Research
Action Research for Teachers
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