Experimental Design - Nitrogen Project

Background for Teachers

Field sampling goes more smoothly with a plan; hypotheses can only be supported with relevant data. Students need to develop a research plan to have that smooth field season and collect those relevant data.

The nitrogen research question deals with time and location, therefore experimental design for these researchers will involve picking a sampling window, or event windows for sampling. Because of the great possibilities in comparing samples from one site with samples from another site, from another school it will be very important that your students characterize their field site well and that they record their field data very well.

Share with your students that they can submit six water samples for nitrogen analysis. They also have access to the data from the other classes doing the project.

Review the Table of Field Variables with the students. If you are in doubt about whether or not a sampling plan is feasible, contact Acadia Learning staff or your partnering scientist.


Students understand:

  • That the hypothesis must be supported by relevant data
  • Collecting relevant data requires a plan


  • Students will produce a sampling plan or a more formal Research Proposal

Where does this lesson happen in the Project?

This is the first Activity in Unit 4: Field Sampling.

Getting Ready

Share with your students that they can submit six water samples for nitrogen analysis.

  • One sample must come from the time of maximum snowpack
  • One from peak stream flow and
  • One must come from the time of complete snow loss (these last two may be one and the same)

If it fits with the students’ research questions all of the samples should be collected between the time of maximum snowpack and the time of complete snow loss. There are always unpredictable issues: Snowmelt all happens suddenly on a weekend, etc. Use best judgment and make notes at each outing to help explain if odd results are produced because of uncontrollable circumstances.

Students will have access to the data from the other classes doing the project.

Review the Table of Field Variables with the students.

Remind your students of the real-time data available to them from USGS National Water Information System website.

Remind your students of any classroom or school limitations (e.g., if you are collecting at six different times throughout the winter you cannot collect samples from someplace that is farther than walking distance).


Students will need to assemble:

  • From Unit 2: Topo maps, hydrographs, soil type and forest cover type, their predictions of maximum snowpack and peak stream flow
  • From Unit 3: Their hypotheses, questions, “data shopping list” or what they need for data

Students will be well served by having the Table of Field Variables so that they know what options there are for data collection resources. If the students have been to the field site then assemble any information already collected.

If they have not been to the site then use Google Earth to look at satellite photos of the site.

Students may also with to consult meteorological forecasting sites such as:

And students will want to monitor the USGS National Water Information System website to watch for changes in flow in their local streams and rivers: waterdata.usgs.gov/nwis/rt (this link does not work, you will have to search for this site and bookmark it)

Note: This site does allow you to set up an alert to inform you when your stream of interest has reached a certain stage. You may want to investigate that.

Handouts (see also Lesson Resources)


Student Prerequisites

  • Students must have their hypotheses and have all of their material from previous Units

Time Needed

1-2 classes (longer if the students write a formal research proposal)

Doing the Activity

Develop the research plan by answering the questions who, what, where, when, why and how. The “why” is the hypothesis. The guiding question for this activity is: How would you go about collecting evidence to support or refute your hypothesis?

Each group should reiterate its hypothesis.

Answer the question in a general sense (if a hypothesis is “Total nitrogen will be highest during the first melt of the winter than later on”, then they might answer: “Collect stream water samples from the time of the first big melt of the winter and at intervals thereafter”).

Craft that general approach into a workable study plan – iron out all the details. Some questions to start with are:

  • How will you find out when the first thaw will be?
  • When do you predict maximum snowpack will be?
  • What else would you need to know about the field site- stream size? topography, aspect, primary tree type, soil type?
  • What other kinds of information do you need to collect/monitor-snowpack depth, stream height?
  • Who will collect the samples?
  • When?
  • How will they be collected?
  • Where will they be stored?
  • Do you want to collect more than six and then choose from the collected samples which ones to send to the lab?

There are more questions. Many more will arise during the process and will need to be addressed. Students should take notes and keep track of how they will address all of the issues.

Each group should present its research plan to the class, and encourage feedback and questions from the other groups. If the project is going to be a class project, follow with a discussion of pros and cons of each group’s presentation, and formulate a coordinated plan for sampling, using a collaborative approach where the best of each group’s methods are combined.

The information the students have put together to this point can be called a research proposal. Students can now be asked to put together a more formal proposal. A research proposal is a document that describes the plan for the project. It makes the case for the proposed study and approach. (Scientists frequently write research proposals and other groups of scientists or people from science agencies judge those proposals to decide which ones deserve funding.)

Once the proposals are completed, students will then have the opportunity to review their peers' proposals with the goal of making constructive, collaborative improvements. Remember, there’s no right or wrong approach to a research project, but the choices students make will determine how they can interpret their results. Alternatively, the teacher or the cooperating scientist can review and make comments on everyone’s proposal.

The following are the general sections that should be included in a research proposal and some questions to answer in each section. Here you’ll think about, collect, and enter information about your project.

Research project title

Give your project a name


 What role does nitrogen play in living things? How does it cycle? Why should we care about nitrogen? How does season affect nitrogen cycling? (3‐4 sentences)


“If _______, then we expect that_____, because_____” (1‐2 sentences)


This section summarizes all the decisions made above – who, what, when, where how?

Results and discussion

What do you think you might find? Maybe you have some ideas because you already have some data. What will your data mean? (2‐3 sentences)

Two sentences:

  • Start with: “If the hypothesis is supported, then… “
  • Start with: “If the hypothesis is not supported, then… “


If you cite (or mention in your proposal) any web sites or articles where you found information (such as your statements about sources of nitrogen pollution, or if you’re using someone else’s methods), you need to list them here.

This document can also serve as a precursor of the final research paper.



Listen as students present. Does their plan make sense? Ask how much time in the field their sampling will take? Which protocols from the Table are they using? Have they read those protocols? Ask them about data management.


Collect the formal research proposals. Review as you would an early draft of a report.

Lesson Extensions and Supplements


Lesson Resources

    Table of Field Variables