Assignment: You have completed an exercise measuring blood pressure and heart rate. You have also studied the respiratory and digestive systems, and are currently studying the immunological and excretory systems. Within your IB syllabus you have studied a variety of factors that can influence variables within these systems. Select one such independent variable, and design your own experiment to evaluate its effect on a named dependent variable.

Design:

Title: State the essential relationship between the independent and dependent variables

Research Question: Continue to describe the relationship between the key variables, but provide enough information about the experimental design to give a brief, but clear snapshot of the experiment.

Key Variables: Give clear, detailed descriptions of each of the variables. These include the a) independent variables which are those that you vary deliberately, b) dependent variables which are those that are affected by the independent variable and whose outcome you measure, and c) controlled variables which are those that you must keep constant during the experiment so that they don’t interfere with the relationship between independent and dependent variables.

Hypotheses: There are two aspects to a hypothesis. First, you make statements predicting the outcome for each dependent variable. This is done in the form, “if x is done, y will result.” Make your prediction quantitative wherever appropriate. Second, for each prediction, you must explain the mechanism whereby the independent variables cause an outcome in the dependent variables. That is, explain why x causes a change in y. Make sure the hypotheses are directly related to the research question. Finally, controlled variables that might affect the outcome should also be discussed.

Apparatus/Materials Selected: Name and describe all of the materials and apparatus used in your experiment in enough detail so that another person could reconstruct the experiment based on your description. Make the descriptions as quantitative as possible (numbers, sizes, concentrations). Create a fully labeled diagram of the apparatus and materials as they will be used in the experiment.

Allows for Control of Variables: Here is where you design an appropriate and realistic experiment. Your design must allow for the control of the variables. How will you control the independent variable so that it varies in a predictable fashion. And how will you control all of the control variables that might otherwise interfere with the presumed relationship between your independent and dependent variables .

Allows for Collection of Data: Be sure that the experimental design and measurement techniques are described in enough detail so that any person attempting your experiment could generate and collect sufficient relevant data. Fully describe the methods for producing the range of the independent variable, for measuring the outcome of the dependent variable, and the number of times you will replicate each trial. If some statistical test is appropriate, name the test. Be certain that your methods are detailed enough that the same data set could be produced by anyone performing the experiment based only on your Methods section.

Data Collection, Data Processing & Presentation, Conclusion & Evaluation:

Over the course of the current unit, you should independently design and perform your experiment. A variety of materials are available in the lab. Seek assistance to obtain additional materials. After you collect sufficient data, continue to write-up a lab report including data processing and presentation, and conclusion and evaluation sections.