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General Science and Teaching

Hypothesis format

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Kathryn Kennedy Kathryn Kennedy 9055 Points

Hi all - I have a question about a 'correct' format for hypotheses. I have many students who transfer in and out of my school and whenever I ask students to form a hypothesis about an investigation, I am usually met with the response, 'That's not how I did it at my old school!'. I like students to rephrase their research question in their hypothesis followed up by a because for their explanation. For example, How does drop height affect the speed of a ball? The ball will have a faster speed when dropped from a higher height because it will have more time to accelerate during the fall. I like this format better than the If...then... approach, because I feel that that is more of a prediction and not a tentative explanation. Does anybody have a format that works well for them and any resources that you've put together to aid in teaching this to students? I look forward to your responses. Cheers! Kathryn

Carolyn Mohr Carolyn Mohr 92246 Points

Hi Kathryn,
That is such a great question, and I am glad that you are asking it. I found this article particularly helpful to me when I was teaching about hypotheses and predictions. I wanted to make sure that as a science teacher I got the two terms straight since I kept hearing them interchanged incorrectly from teachers in other content disciplines: When a Hypothesis is Not an Educated Guess. It is a must read for teachers who want to be sure they are using the terms accurately with their students. The article also explains each term separately and gives good examples. What you think is going to happen is different from how you think something is going to happen, so the two terms explain two different ways to look at a problem's outcome. Personally, I like teaching the kids the IF...then... format. I like how you phrase it, too. But I think there is something to be said for uniformity across the nation. It may make it less confusing for our students who move a lot - to see it being taught in the same format. How are others introducing these two different 'science process skills'?

Kathryn Kennedy Kathryn Kennedy 9055 Points

Hi Carolyn - Thank you for sharing the article about hypotheses and predictions. I found the article extremely useful for those terms. I feel as though the article did validate my decision to use the format that I teach my students today because they are trying to actually explain their explanation and not predict what will happen for the specific test. However, I found the authors spreading themselves too thin within their article when they then decided to introduce the terms law and theory. That's an entire journal on its own! Have you come across a resource that discusses the terms theory and law? I would enjoy reading another article that you've found useful. Thank you again for sharing!

Carolyn Mohr Carolyn Mohr 92246 Points

Hi Kathryn,
Yes, I have found this article by Dr. Bill Robertson extremely helpful in explaining theory vs. law. Enjoy: Science 101-How does a scientific theory become a scientific law?
I think you would like EVERYTHING that Dr. Robertson has written. He is the author of the Sop Faking It series available in the NSTA book store. There are several free chapters of his books available in the Learning Center, too.
My Best,

Sandy Gady Sandy Gady 43175 Points

Kathryn, I really like the way you use the hypothesis format. In reality, you are basically doing the same as the If … Then … but it appears to me to be done in a way that supports not only good thinking and Science, but also helps students see the value in writing precisely and concisely in Science. Science is one of the few areas where we can teach students to write in a genuine manner for a different audience than they would ever see in their Language Arts classroom. It is so important for students to not only have an idea what may occur as a result of the investigation, but to be able to formulate those thoughts into a Science related “reason”. With my middle school students, I call the second part of the hypothesis the “Science of Why”. I force students to think in a critical manner on their thoughts and to use the Science vocabulary that accompanies their explanation. While this is difficult for many at first, with a fair amount of practice they get really good at it.

Gerry Clarin Gerry Clarin 2125 Points

I had a former student come to my room he majored in Biology and he told me that colleges don't like the If then because format. I teach High School Biology and I like using the If then Because format for writing a hypothesis. It's clearer to me and the students. I know colleges are discouraging teachers from using the if then because format. Does anyone know the reason behind this?

Katherine Willet Katherine Zimmerman 21340 Points

Does anyone have a uniform format you use with the department at your school? I was having this discussion with my teachers the other day. We are finding our students struggle on the standardized tests because they are hearing so many different definitions and formats for scientific inquiry. I have always used "If ___ then ___, because___" with my students so they are able to articulate the educated part of their guess. As we were talking, the teachers in the next grade level were frustrated that I had been teaching the students that format because it did not line up with what they had been teaching. The same thing was true for terms we all use with students. We are starting to create a "Science Dictionary" for our school. Has anyone else done something similar, or how do you handle different definitions/formats for common terms?

Nicole Dainty Nicole Dainty 4360 Points

Good question Kathryn! Personally, I teach my students that your hypothesis is a possible answer to the question you are investigating, and that it's not a guess - it is based on the observations, experience, and research you've already done. When I have students complete a lab, we always start with a question. ('Will the motion of a balloon rocket change when more air is used in the balloon?') Their hypothesis is a possible answer and must include their reasoning. ('If the balloon rocket is propelled with a greater volume of air, then it will accelerate at a faster rate because there is more force acting on the balloon.') Having them include their reasoning helps me to see what background knowledge (or lack thereof!) may be affecting how they are interpreting their results. Or, sometimes, I find that all the students knew what would happen, which tells me that I can do a lab that is more complicated, or looks at a topic in a different way.

Nancy Burcham Nancy Burcham 50 Points

I have always used the If... then... because format for teaching my middle school students to write a hypothesis. It helps emphasise the cause/effect relationship and identify the Independent and Dependent Variables. The because statement helps identify if they are basing their ideas from observation, research, or are just guessing. Recently my 5th grader brought home the directions for his science fair project and he is being told that the the hypothesis is an "I think.." statement and the prediction is an If... then... statement. They are not required to give a reason in either statement. My teaching partner recently went to a workshop where she was the only secondary science teacher and she said she was shocked to hear the same definition of hypothesis and prediction. Is this common in elementary school? It seems confusing to me as adult and I would think it would be especially confusing to sixth grader.

Chris Leverington Chris Leverington 4035 Points

We use if...then...because. The reason for the if, then is that it needs to be testable.

Kacee Ertzbischoff Kacee Ertzbischoff 10 Points

If...then...because is the format we use but we teach EXPLICITLY that it is not all a hypothesis. I teach If is the procedure, then is the prediction, and BECAUSE is the hypothesis because a hypothesis is an explanation.

Alyce Dalzell Alyce Dalzell 64075 Points

Hi, We have debates with this structure throughout the 3 levels of schools in my district. The If...Then... Because... is used as a base point to instruct and support students in writing testable predictions. I would not encourage/allow my high school students to use this format - nor do high school educators throughout my district. During 8th grade our students begin transitioning in their write-ups to prepare for their high school coursework. I would try and facilitate a discussion among elementary, middle and high school science teachers from your feeder schools to gain knowledge on their standing - and move on from that point. Hope this helps, Alyce

Kathryn Kennedy Kathryn Kennedy 9055 Points

Hi Alyce - Thanks for posting on this idea. Are you able to share a few of the acceptable formats that you use at the high school level? I still struggle in how to address hypotheses with my students. Especially now after reading Dr. Robertson's article, "How does a scientific theory become a scientific law?" I look forward to hearing what you allow in your classes. Cheers! Kathryn

Eric Wilson Eric Wilson 10 Points

I realize this topic has not seen much activity for a while, but I wanted to chime in real briefly. I'm a doctoral student in science education (I taught primarily 8th grade when I was a classroom teacher). As part of my research assistantship I watch video of math and science teachers. One teacher used the "If. . . then . . . because" format with 5th graders. I was struck by how the "because" was almost always completely unverifiable. This concerns me when having students provide a "because." As many people stated, a hypothesis is NOT a guess, even an educated one. It is indeed predicated on observation and previous knowledge, which this teacher also asserted, but the use of "because" introduced a concept that may or may not have scientific validity and may or may not be testable. It is this latter part that is so worrisome. If the whole point of a hypothesis is to test it in order to determine its accuracy, then how can a "because" statement that may not have any connection to what is being tested be allowed? I hope this makes sense. When teaching the "If . . . then . . . because" I would argue lots of care needs to be given to the "because." However, I think a student fleshes this out in their discussion/conclusion, even at the primary and middle school levels. Hope this helps the conversation.

David Hanke David Hanke 2395 Points

I also use the If...Then format. 2 of my 3 bio classes are basic biology level classes and they seem to understnad this format better. I also like this because when I ask students to read a passage and then pick out the control, the independent and the dependent variables, I tell them that by remembering that the If is the Independent and the Then is the dependent variable. A bit corny but also If and Independent both start with the letter "I", so sometimes this helps students remember too.

Pamela Auburn Pamela Auburn 68625 Points

Eric, I share your concern. A hypothesis should predict how two things are connected to each other. A hypothesis is a sentence which shows us how two different things are connected. Here is an example: the more water a plant gets, the faster the plant will grow. In this example, we are connecting two things: 1) quantity of water and 2) speed of plant growth. When writing a hypothesis sentence, there are generally four kinds of sentences: the more this, the more that the more this, the less that the less this, the more that the less this, the less that It is important that BOTH things being connected can be measured. I prefer this format to if____ then____. The If, then format does not clearly imply the necessity of measurement.

Angelo Laskowsky Angelo Laskowsky 2190 Points

Wow, who'd have thought that something like the format for a hypothesis would spark so much discussion! I teach my kids that hypotheses have the format: If (the independent variable) is (measurable verb) then (the dependent variable) will (measurable verb) because (short rationale for this hypothesis based on observations or information they have learned in their research). I look over every hypothesis (later on, the kids do this themselves in pairs) to make sure that everything is measurable, and that the rationale is scientifically logical. The scientifically logical part comes from their research on the topic (notes, an earlier learning experience in the class, or a demo/video).

Jennifer Rahn Jennifer Rahn 67955 Points

Angelo, I like your approach. Understanding science begins with observation, which helps us understand how the dependent variable is related to the independent variable. As a former working scientist, the "because" clause may not have been an explicit part of the statement of hypothesis, but it was always implicit in a proposed study. Of course, we also had to provide measurable inputs and outputs, and expectations of statistical ranges. The hypothesis often grows to a paragraph, properly explained.

Maureen Stover Maureen Stover 41070 Points

Hi Everyone, Eric, thanks so much for re-igniting this discussion. I didn't see it when it started several months ago, but I'm so glad that I've now found it! As an elementary level teacher, I struggle with the best way to introduce my students to experimental design in a way that 1) they will understand, 2) promotes inquiry, and 3) prepares them for secondary and post-secondary science courses. As I've worked to revamp my teaching style to align with these educational goals, I've discovered that beginning experimental design with testable questions and predicting outcomes based on prior knowledge and/or research has worked well for me. I'm curious if other teachers have similar experiences? I noticed that Alyce discussed trying to align the way her district approaches hypothesis writing across grade levels. Are other schools/districts doing this as well? Also, does anyone have any suggestions for ways that elementary teachers can introduce experimental design to provide for a smooth transition into secondary science classrooms? The shift in today's classroom toward inquiry is extraordinary. I love seeing my little scientists explore, investigate, an learn through hands-on activities that encourage them to problem-solve. I'm always looking for better ways to prepare my students for higher education and real world applications. I can't wait to hear all of your fantastic suggestions. Thanks! Maureen

Angelo Laskowsky Angelo Laskowsky 2190 Points

@Jennifer, Hmmm.. I think you guys have helped me a lot. I was looking through my old high school and college research papers, and I never included a 'because' clause in my hypothesis. My Introduction always had the 'because clause'. I would write something like "because of these observations, it is hypothesized that....". I think that's what I need to shift towards. I have no clue why I started teaching that a Hypothesis needed a 'because' clause. maybe, it's because that was the party line of the school when I came in. And, being a new teacher, I just accepted the older views as fact.

Angelina Cruz Angelina Cruz 820 Points

Hi Jennifer, I started teaching scientific method requiring them to write hypothesis using "If___then___" statement. However, after years of pondering, I figured it will be more scientific if students will include the "because" part of the hypothesis where they can write their justification using various available resources like websites, books, magazines, and journals. With the addition of the justification, students are exposed to science words. It allows them also to write them using their own words and avoid plagiarism. Angie =))

Angelo Laskowsky Angelo Laskowsky 2190 Points

Heya Angelina! Ya, we did start doing it that way, didn't we? I agree, though, having their because really helps them cement their thinking and prevents copying. To everyone: It seems like everyone has 2 different ideas: providing a rationale to support the hypothesis; and keeping the independent and dependent variables distinct and no extra variables are put into the hypothesis by the because. So, I guess the best solution, is to do both? I should move the 'because' to the introduction/background section of my lab reports and keep the if/then in the hypothesis with measurements. So now, I have to ask how detailed should the hypothesis be? Like, should I have my students include the increments they're increasing the temperature (Say, in an experiment in which they're testing the effects of temperature on the rate of the chemical 'weathering' of chalk)? Or, will a generic statement that temperature will be increased from room temperature to about 80 C suffice?

Fred Dyer Fred Dyer 60 Points

I don't know if this thread is still live, but I hope some of you will respond to this. I am a biologist, and many years ago I developed an exercise for college students on how to understand the scientific method. Two summers ago I presented this exercise to high school science teachers from Michigan, and one of them raised her hand and said she thought that hypotheses had to be stated in the form of "if-then=because." Many of the other teachers nodded their heads in agreement. My response was "huh?" I had never heard this. It was not how the scientific method was taught when I was in school many years ago. It is not the way scientists think about hypotheses. It is not the way they state hypotheses in scientific papers. I think if-then-because is confusing because it lumps together a statement of the hypothesis (the part after the "if") with a statement of a prediction of the hypothesis (the part after then "then"). I can explain further if people are interested. For now, however, I am really interested to know where the "if-then-because" notion came from. Is there a book or two you can refer me to, especially one that would lead back to the original source? Thanks very much.

Chris Leverington Chris Leverington 4035 Points

Fred, I'm not exactly sure where the whole if, then because hypothesis format came from. I remember being taught if, then. I would guess that this came about due to the kids inability to properly identify the variables (independent and dependent). If you phrase it in the if, then format; the if portion is your independent variable and the then portion is your dependent variable. I would say the "because" portion came about to make the kids explain their logic behind their hypothesis. For example, in my chemistry class last week the students created an experiment to test factors that affect rate of solution(dissolving). Most kids could easily hypothesize that if I heat the water up that things will dissolve I wanted them to explain why they thought that. It makes sense that in the "real" world that scientists wouldn't use this format. You already know what your variables are and you know the reason for your hypothesis. I've been told over and over again that "scientists" don't use the scientific method. But we have to have some sort of standard to base the education off of. The if, then..because format helps us to get the students thinking aligned to a common standard and make them think about the hypothesis that they are putting forward. I'd really be interested in learning about/seeing your presentation though :)

Fred Dyer Fred Dyer 60 Points

Hi Chris: I appreciate your thoughts on my question. Just to clarify one thing...I would never say that scientists don't use the scientific method. I have heard/read that too, but I think it is incorrect. What is correct is that for experienced scientists, the logic of the scientific method comes so easily and fluidly that it looks like they leap over steps that might need to be spelled out to people who are less experienced (such as K-12 students). My concern about If/Then/Because statements is different. I think this framework blurs together steps in scientific reasoning that are worth keeping separate, and that most experienced scientists do keep separate. In an if/then conditional such as "If P then Q," P is the hypothesis and Q is the prediction (the thing that you would expect to observe if the hypothesis is true). Why state the hypothesis and the prediction separately? Two reasons: first, it might be that the hypothesis makes multiple predictions (for example, the hypothesis that heating the water affects the dissolution of a solid might predict not only that a substance would dissolve faster when you heat the water but also that more of the substance would dissolve--two different things that can be measured); second, it might be that the prediction is made by more than one hypothesis--this is often true in complex systems such as biology, although perhaps not in your chemistry example. As for the "because" part, I agree that it is important for a student to have an understanding of why the hypothesis is a good explanation for the phenomenon being studied. I would appreciate any other insights you or anyone else might have into how the if/then/because formalism got started or even where/when you were taught it. If you do a Google search on the terms if+then+statement+hypothesis, the vast majority of the hits are sites that are produced by or for K-12 teachers. I'm thinking that this got started as part of teacher training sometime in the past 20 years. I would like to write an article about this issue, and it is for that reason that I am hoping to find the origin of the practice. Thanks again.

Chris Leverington Chris Leverington 4035 Points

I'm don't agree with your "If being the hypothesis and then being the prediction" assessment. I see the If as a condition and the then being a "prediction" So for my chemistry situation. If the temperature of the water is increased, then the substance will dissolve faster" I was in high school in the late '90's and I'm trying to remember what I was taught. I don't think we did the "because" portion. But we had to support our hypothesis with evidence or information. I think in the basic way labs are approached in schools today, the if, then format suffices. I would think that if students were doing a more advanced individual scientific research project that we would approach that differently, where they would have included a research section in their report.

Fred Dyer Fred Dyer 60 Points

Hi Chris: I agree that in everyday language people may say "I hypothesize that if I do X I will see Y." By itself that is a prediction of an outcome given a particular action, not a prediction given a particular scientific explanation (e.g., of what increases the rate of dissolution). For this kind of if/then statement the words hypothesis and prediction could be used interchangeably. So, in your chemistry example, you could say "I hypothesize [or I predict] that if I turn up the heat the solid will dissolve faster." But you could also say ""I predict/hypothesize that if I shake the container the stuff will dissolve faster." So, two different procedures could cause the same outcome. Are they two different hypotheses? Possibly--two different causal mechanisms might cause the same outcome. Not in this case, of course. It is the input of energy that increases the rate of dissolution, and you can do this either by turning up the heat or shaking the container. This is an example of how adding "because" to a statement about the predicted effect of a procedure would help, since it would explain the basis for the prediction. So you could say "I predict that turning up the heat will make the stuff dissolve faster because of the input of energy" But look what has happened: the actual hypothesis (the physical explanation for what causes the solid to dissolve faster) comes after the "because" in the sentence. Even more confusingly, you could reword the statement and say "If the input of energy from heating speeds up dissolution, then turning up the heat will cause the solid to dissolve faster." So now the physical explanation--the answer to the question of what influences the rate of dissolution--is after the "If" and the procedure and its predicted effect are after the "then." Or you could say (as one author recommends), "If the input of energy from heating speeds up dissolution, and you turn up the heat, then the solid will dissolve faster." So the if/then statement by itself might not contain the physical explanation (in the case of a "because" being needed to complete the logic), or, if we put the explanatory logic into the if/then statement, the statement doesn't specify reliably where the causal explanation can be found. What I recommend to students is to start with the question: e.g., "What speeds up the dissolution of a solid?" Hypothesis/es: Heat (or shaking, or, more general, input of energy) Prediction of hypothesis: Turning up the heat (or shaking it) will cause the solid to dissolve faster. I really have valued this exchange of ideas. It is making me think hard about where my assumptions come from. I still want to know where the if/then/because notion came from. Before the 1990s (when you were in high school), and after 1973 (when I graduated from high school), apparently. Thanks again. Fred

Jennifer Rahn Jennifer Rahn 67955 Points

Fred, I'm with you on this one. I think you are right about it appearing after 1973, because I don't remember seeing it in high school science, but it did show up in rules of argument. It was part of the rules of building an argument for debate (yes, I was one of the geeks carrying around a box of cards with data and arguments for rebuttal). The next time I saw them was probably when I started doing FORTRAN programming (remember that?) and we had to build processing logic including forks and loops. But all the way through grad school I never remember seeing the If-Then-Else used for hypothesis testing. At least at the college level, statement of an hypothesis usually involves a statement of probability, relationship, and causality. Nothing in the real world is as direct as high school science would have us believe! The most interesting think, at least from my perspective, is that the concept of hypothesis development and testing is as important in social science as in physical and natural science. Most of what I learned about the design of hypotheses came from graduate research design classes in education and business. The "scientific method," as we call it, is used in all manner of research where we seek statistical validation of correlation of independent and dependent variables. I work with a lot of students in statistics. One of the most important definitions encountered very early is the difference between null and alternative hypothesis. We design a test to determine the relationship; based on observed behaviors or outcomes, we can either accept the relationship at a level of certainty (never absolute) or reject it. But sometimes we reject "true" relationships, and other times we determine the opposite. There is never an absolute in testing hypotheses; only a level of probability. I may have gone off the deep end a bit, but I do not believe I have ever seen an hypothesis stated in the if-then-else format for research at any level other than K-12, and perhaps some intro-level science classes at the college level, especially where students do not have an understanding of statistics - except, perhaps, teacher methods and practicum classes.

Pamela Auburn Pamela Auburn 68625 Points

Fred, You might be interested in Science Wars: What Scientists Know and How They Know It

Nicole Dainty Nicole Dainty 4360 Points

Fred -

I have drawn on two sources after completing my initial teacher training to develop how I ask students to write their hypotheses and predictions - both more recent than the 1970s.

They are: (check their hypothesis advice for students. This site is intended to help students with inquiry process during science fair.)

Also Using Science Notebooks in Middle School by Klentschy

Both use the If/Then statement.

I have had my student use the 'because' phrase as well, and have also found it a bit problematic, because it seems like it is written for a teacher audience rather than an audience of peer reviewers, as scientific papers are. I believe Christ discussed this aspect as well. It is sometimes helpful for me as a teacher to know why my students are making such predictions, but I agree that it doesn't seem to reflect how scientists work and that's what we should be aiming for.

I too would be interested in hearing more about how we can help students to keep these ideas separate as they are learning the scientific process. If there are resources or ideas you'd recommend, please let us know!

Fred Dyer Fred Dyer 60 Points

Hi folks: Response to Jennifer: I definitely think that a scientific hypothesis has to have a statement of causality. For this reason, the discussion of hypotheses in statistics confusing things further. The null "hypothesis" is that a difference between two samples could have been produced by a random process, while the alternative "hypothesis" is that a difference between two samples couldn't have been produced by chance. Such hypotheses say nothing about causation, although the experimental design may involve a test of a causal hypothesis. One of the statistics professors here at MSU is the person who pointed out to me that statistical hypotheses are not scientific hypotheses. What's a poor student to do with such a situation!? Response to Nicole: I'd like to rephrase part of what I said in response to Chris, about how the If/Then approach by itself doesn't make the causal hypothesis clear. Consider three different formulations (1) "I predict/hypothesize that if I increase the temperature of water, then a solid will dissolve faster." This predicts the consequence of a procedure, but there is no causal explanation here. You need something else to explain why you are using this hypothesis in favor of one such as "I predict/hypothesize that if I recite love poetry to the water, then a solid will dissolve faster." You would need a "because," for example "I predict/hypothesize that if I increase the temperature of water, then a solid will dissolve faster because of the input of energy." So the causal explanation (the scientific hypothesis) is really not the part after the "if," it is the part after the "because." (2) "If the input of energy from heating speeds up dissolution, then turning up the heat will cause the solid to dissolve faster." Here the physical explanation--the answer to the question of what influences the rate of dissolution--is after the "If" and the procedure and its predicted effect are after the "then." This is what I was thinking of in my original post. In this case a causal hypothesis is being stated without the word "because." (3) "If the input of energy speeds up dissolution, and you turn up the heat, then the solid will dissolve faster." One author I read in the Science Ed literature recommends this formulation. Here the causal explanation is after the "if" and the procedure is before the "then" instead of after the "then." There is no "because" but there is a causal hypothesis. Bottom line: "If/Then" and "If/Then/Because" by themselves don't tell you where the actual scientific explanation is in the sentence. It all depends upon how you word it. That's one reason I worry that a simple prescription to use if/then statements could be confusing. See my response to Chris for a simpler way to go about it. Fred

Ali Neugebauer Ali Newgebauer 1170 Points

Hello all- I just wanted to say thank you this thread. I am discussing with my students today how to write a strong hypothesis and I found your recommendations to be helpful.

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