The Process of Scientific Inquiry WESTERLY MIDDLE SCHOOL SCIENCE 2010-2011

Review…

Writing Experimental Research Questions Compare experimental sample vs control sample Must include independent and dependent variables and a subject: The independent variable is the variable that the researcher selects or changes to determine if it produces changes in the dependent variable **A researcher looks for evidence that changes in the independent variable are correlated with changes in the dependent variable Must also include conditions – the parameters (structure/limits) under which the study is conducted and may include any of a variety of key factors such as temperature, light intensity, and pH…

Dependent Variable Independent Variable

Writing Experimental Research Questions - Formula “What is the effect of (independent variable) on (dependent variable) in (subject) at (conditions)?” “What is the relationship of (independent variable) to (dependent variable) in (subject) at (conditions)?” Plant Height Temperature Plant Type Bean Plant Sunlight Fertilizer Mazda Miata Weather 405 North Tire tread Time to go 0 to 60 mph Independent Variable What you decide to vary in your experiment Dependent Variable What changes as a result of the independent variable changing Conditions (Control Variables) What stays the same for all trials – environmental/location/time/ etc. Subject The subject you are looking at / observing

Prediction and Hypothesis (sh) Hyopthesis: General e.g. All swans are white Expt prediction: What will happen in one given case, e.g. the next swan I see will be white. Prediction and Hypothesis (sh) “A hypothesis should be considered as a statement based on an analysis of data or events that have occurred in the past.” “…a prediction is actually a conditional statement made by the students focusing on what they think will happen as a result of conducting an investigation or describing what they think would be a reasonable answer to their focus question.” Hypothesis: [General e.g.] All swans are white Prediction: [What will happen in one given case, e.g.] the next swan I see will be white because… "…not only state what [you] think will happen, but also write a reason or explanation for what will happen based upon prior knowledge.” How to start writing predictions: Can draw a diagram, picture, or illustration of what you think will happen I think (or predict) _____ will happen because _____. If _____ then _____, because _____ Good predictions should: Propose a possible answer to the focus question; Be written as a conditional statement; and Provide an explanation or reason based on prior knowledge conditional statements

Prediction and Hypothesis (sh) Focus Question: “What is on the bottom of the cube?” After making observations and gathering data, did you make a prediction or form a hypothesis? Recall: Good predictions should: Propose a possible answer to the focus question; Be written as a conditional statement; and Provide an explanation or reason that both activates prior knowledge and gives the science teacher insight into current student misconceptions I think _____ because ________.

Developing a Plan Stage 1: The General Plan Identify the variables in the system being studied and determine what will be changed (the independent variable) what will stay the same (the control variables), and the outcome to observe or measure (the dependent variable) “fair test – when only one thing (variable) is changed for the investigation.” Stage 2: The Operational Plan The sequence of procedures, events, or steps that will be taken by the student during the investigation. Can include the materials used for the investigation

Developing a Plan The General Plan: List the variables you are examining: ________________ _______________

Developing a Plan Data Organization: ask yourself: How will you collect your data? What will you use to collect and record your data? What will your data collection device look like?

Criteria for Data Collection (student handout) Tables must be clear and easy to read Must have a title that describes the data in the table Columns and rows should be clearly headed When appropriate the left column or top row should contain the independent variable and the bottom row or right column should contain the dependent variable. Units should be displayed in column/row headings only. Missing values should be displayed as -, and zeros as O. There should be no blanks in a table conveying experimental results. Numbers should be listed neatly below each other and should be to the same number of decimal places.

Graphs are used to: (student handout) Communicate information to other people Identify trends in different variables (interpretation) Identify how one factor affects another (correlation) Help understand what the data represents (analysis)

Graphing Guidelines: (see handout) Determine what type of graph to construct: line, bar? Always give your graph a title. The x-axis of a graph is always your independent variable and the y-axis is the dependent variable. Use a ruler to draw your axes. Always label the x and y-axes and units and space them evenly. Where the scale does not go to 0, use a broken axis. Equal intervals on the scale must represent equal numerical values. Make a best-fit line or curve to follow your data for line graphs graph. Make sure your data is graphed in an area as large as possible, centered on the paper. Make your graph clear and neat.

Line Graphs: (see handout) Are good at showing specific values of data, meaning that given one variable, the other can easily be determined. Show trends in data clearly, meaning that they visibly show how one variable is affected by the other as it increases or decreases. Enable the viewer to make predictions about the results of data not yet recorded through either interpolation or extrapolation. Lines are usually either straight or curved – close to all points = “best-fit”

Bar Graphs: (see handout) Are best used for comparing data quickly and easily, such as the density of different substances or the growth of plants in different pots. Show how one variable is affected by another characteristic

Example expectations for graphs: The independent variable is plotted on the x-axis The dependent variable is plotted on the y-axis Decide on an appropriate scale for each axis Label each axis: Put the specific and general independent variables on the x-axis Put the dependent variable and the unit of measurement on the y-axis Plot your data. Title your graph with a descriptive title (ex. A comparison of…) Describe the graph: Why did you choose to use a bar/line graph to show your data? Did the graph turn out as you expected? Do you believe this was the best graph to use to represent your data? Why or why not? What does the title say? What is on the x-axis What is on the y-axis? What are the units? Describe the data: What is the numerical range of the data? What is the graph telling you? What kinds of patterns can you see in the data? How can you describe in words what the table and graphs represent? Interpret the data: What does the graph show you about your prediction? How do the patterns you see in the graph relate to other things you know?

“Interpreting Graphs” For each of graph, identify (1) the independent variable,  (2) the dependent variable (3) give a simple interpretation of the data. (4) list things that must be held constant, (5) describe an experiment that would produce such data and Activity 5.5.1 – Interpreting graphs

Demonstrate by walking:

Matching Stories with Graphs: Select the graph that matches the scenario A commuter bus stops at a series of major intersections

Matching Stories with Graphs: Select the graph that matches the scenario A swinging pendulum experiences substantial friction. Friction is a force in the opposite direction of motion – acts to slow the motion

Matching Stories with Graphs: Select the graph that matches the scenario A driver cautiously accelerates from a stop sign and enters a freeway

Matching Stories with Graphs: Select the graph that matches the scenario A rocket engine fires continuously on a spacecraft in orbit around the Earth

Creating Stories from Graphs Distance versus time graphs for runners in a marathon. Write a plausible story for each runner that can explain the corresponding graph 20.3.2

Creating Stories from Graphs The water level in a small child’s swimming pool as a function of time on each of three days Write a story to explain each.