 background for teachers a hypothesis or scientific claim is simply a well reasoned guess at the answer to your research question the words well reasoned are important here a well reasoned claim usually includes a because statement or takes the form of an if then statement for students to develop a such a claim it should grow out of some kind of a model of the system or mechanism under investigation a student ought to have some idea as to why the outcome predicted by the hypothesis would happen example suppose a student offers a scientific claim that mosquitoes would have higher mercury levels than beetles then suppose you ask the student to explain why he or she expects this outcome if the student simply says i don t know it s just a guess then there is no model in place and when the student actually gets the data back from the lab all that he or she will be able to say is either good i was right or huh i was wrong but if the student has a model of how things work that is informing that scientific claim saying for example that since mosquitoes get their food from animals some of which are carnivores they are effectively high on the food chain then there is the possibility of having some learning happen if the data support the hypothesis you might suggest that the student compare the mercury level of male and female mosquitoes to see if the blood is what makes the difference if the data do not support the hypothesis often a more interesting outcome you might suggest that the student try looking exclusively at female mosquitoes or compare the mercury level in mosquitoes to that found in other insects and so on the point is that the model behind the hypothesis gives you something to build on coming up with a hypothesis we have found that students have difficulty coming up with a hypothesis that they can work with perhaps some of the problem is that hypothesis is a formalsounding word an approach that has worked has been to have the students review their learning so far and then ask i wonder and then i think and have students do this often hypotheses often come from a continuous refinement of ideas have the students start with the question that the class is looking at suppose for example that the question is how does mercury end up in living things in a forest we suspect that a lot of the trouble that students have is in moving from this kind of general question to the more specific kind of assertion that makes for a hypothesis just as in our discussion of well reasoned guess above what is missing is the model so you would probably want to have the students draw a picture of how they think mercury moves in the forest  see the mercury in foodwebs classroom activity  where does it come from and how does it enter the food chain different students will come up with different pictures or models of course but suppose that a group of students has the mercury captured by the trees washing to the ground moving into its methyl form in a boggy area getting absorbed by plants in the bog moving up into insects that feed on vegetation in the bog and so on that model is what generates some hypotheses with a model the students can ask if the model is correct what would we expect to see would the algae and plants in the boggy area contain more mercury than other plants what kinds of insects or other animals feed in the boggy area would they have higher mercury levels than upland insects and so on the hypotheses grow out of following out the implications of the model once again if the model is correct what would we expect to see so how do the students go about constructing a model they already made a start at this at the end of unit 2 when they drew diagrams of the mercury cycle for whatever system it is that they are studying some of the information required to understand and extend this diagram comes directly from the course content that you provide using the resources in these lesson plans the class text and so on another part of what the students need will come from additional reading about the plants amphibians and other forms of life in the system that they are studying the key thing is to have the students try to draw a picture of how the system works when there is a part of that picture that is fuzzy or that they don t understand they need to do some more reading or devise an experiment to find out what they need to know note by the way that the model that the students come up with does not have to be true in some final sense it just needs to hold together make sense and serve as a good foundation for their continued thinking and research the degree to which you want to interfere and correct a model is another one of those judgment calls that depends once again on whether the model is owned by the students on the right topic pedagogically useful a hypothetical chart it would be a good idea to have the students make a chart or graph of what they think the results of their datagathering might be this would give them an indication of the viability of their hypotheses they should draw the graph on a piece of paper rather than use a computer they will need to decide what information goes on which axis and plot what they think the data will show for example say a student hypothesized that mosquitoes will have more mercury than beetles because mosquitoes feed on carnivores which are higher on the food chain here is what their hypothetical chart would look like    a good resource  we have found that a simple  claim reasoning and hypothetical graph  worksheet coupled with classroom discussion and peer review help with developing scientific claims goals challenges the goal is to guide the students toward a specific research question a question that they can investigate by setting up an experiment collecting data and analyzing the results teachers need to guide this process so that the students questions meet a few important criteria  owned by the students  students should develop their own questions because they will learn from doing so and will be more invested in the research outcomes on the right topic  on the other hand the students questions need to be consistent with the learning objectives for the course for example if the course is focused on food webs you might not want to let a student pursue a question about whether you catch more bass in deep water than in shallow water  unless the student connects that question to food webs pedagogically useful  you will also want to be sure that the questions that students are pursuing are ones that they can hope to investigate given the time and equipment that is available and given the students level of expertise you are trying to direct the students toward a positive outcome and you want to steer them away from paths that are likely to end in frustration or in a trivial uninteresting result balancing these objectives requires judgment familiarity with the scientific principles involved and practice you the teacher are acting as a guide for the students on an intellectual adventure some journeys inevitably turn out to be more interesting and exciting than others the more times that you lead these trips the more you will know about what works this is one of the key reasons that we are asking you to share your experiences both good and bad with other teachers by pooling experience you can learn from each other so please post your hypothesis development classroom practices in the forum so that we can all learn from each other  mercury in watersheds hypothesis background for teachers  