OLE Hypothesis Writing

I have difficulty with hypothesis writing. Different sources suggest different formats and I cannot find one that “works” for all students. So, I adjust for my students. You may completely disagree, and that’s completely okay! For middle schoolers I focus on the intent of a hypothesis rather than the defined structure of the sentence.

What is the intent, you may ask? A hypothesis is an informed statement about what the researcher believes will happen in the experiment. The background information provides clues, if you will, about what will happen. Because I want students to make the connection between the background information and their predictions,  I am purposeful and direct about the process. Students in my class take the ideas from the background information and use those to support their prediction. The hypothesis tells me what they anticipate the outcome to be and WHY.

A hypothesis must be testable. This may seem obvious, but it takes some discussion in the classroom to explain what that means. For continuity sake, I am going to continue on our forest fire example. Here are a few potential hypotheses to work with:

  1. The soil with the most ash will be the worst.
  2. The soil with the least ash will be the best.
  3. The ash will not affect the soil quality.

I would not accept any of these as a final hypothesis. However, they have starting points and that is helpful. Words like best, worst, and quality show up all the time on rough drafts. This is a great opportunity for students to dig deeper. What do you mean by worst? How will you measure worst? What are you comparing it to? What in your background information brought you to that idea? Can you tell me more about the characteristics of soil quality? These questions, and more, could be provided by me, but might be better received from classmates in a small group feedback session. I would model this to begin, and then ask students to share in small groups. I would also ask them to jot down initial responses to these questions in their OLE journals so they have them to reference later.

Maybe a better hypothesis for our investigation would be: The soil with one centimeter of ash on top will hold more water and contain a balance of nitrogen, phosphorous, and potassium beneficial for plant growth compared to soil with no ash or more than one centimeter of ash. According to my research (insert citation from background information), plant growth increases when soil contains even amounts of N, P, and K. Plants also require water for photosynthesis. One centimeter of ash will provide the nutrients and decrease water loss due to evaporation, therefore benefitting the soil for plant growth.

Is that too much to expect from a middle school student? In a rough draft, yes, but after a feedback session and with time to process and revise, no.

Another benefit of a hypothesis written with detail is it leads toward a procedure. I know from the hypothesis the group will use varying amounts of soil as their independent variable. They will measure NPK levels and soil moisture. And, I would guess they will attempt to grow plants in each of their plots in order to measure plant growth.  If they had left the hypothesis as #2 above, the procedure would not have come forward so easily.

Thoughts? I would love to hear them 🙂

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