1. Describe the trend shown in the graph. What two quantities are related, and how? 2. Take out your graphing homework. Work with someone next to you to pick one graph that you think would be useful for data analysis and explain why.

Data = Observations & Measurements Data is a group of related measurements or observations that can be used to support or refute a hypothesis. A hypothesis is a possible explanation of some behavior or phenomenon.

Graphs Represent Data Visually Graphs are a way to show data to someone else in a way that is more meaningful than a table or chart. Graphs make it much easier to identify trends in data.

Question: Does Increased Light Cause More Photosynthesis? Photosynthesis is the process plants and some other organisms use to capture the energy of sunlight and use it to grow. Photosynthesis produces oxygen gas. Hypothesis: Since photosynthesis requires light, more light will allow more photosynthesis to happen. Since photosynthesis also produces oxygen gas, we will see more bubbles if we shine more light on an underwater plant. If there’s more bubbles when there’s more light, then we have support for our hypothesis!

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Virtual Experiment: Water Weeds lations/waterweed.htm lations/waterweed.htm To access link ctrl+click. Requires Adobe Shockwave 32-bit. (Use Microsoft IE) If unavailable, use the data that follows this slide.

Data Table 1: The effect of light intensity on photosynthesis

Variables in Experiments If only one variable is changed at a time, its effect can be measured without interference from other factors. Constants Remain The same. Independent Variable values selected by experimenter Dependent Variable is the “unknown” values being measured.

IV vs. DV The DEPENDENT VARIABLE is the measured or observed result. The INDEPENDENT VARIABLE is known before the experiment begins.

The Effect of Light Color On Photosynthesis Now, investigate the effect of a different independent variable: light color. Which color of light do you hypothesize will make photosynthesis happen fastest? white redgreenblue

Run the Simulation Yourself… or… Data Table 2

Line Graphs vs. Bar Graphs Line graphs show how the dependent variable changes across a range of the independent variable. THE INDEPENDENT VARIABLE IS THE HORIZONTAL X- AXIS THE DEPENDENT VARIABLE IS THE VERTICAL Y-AXIS Bar graphs represent data grouped into categories. – THE INDEPENDENT VARIABLE IS THE HORIZONTAL X- AXIS – THE DEPENDENT VARIABLE IS THE VERTICAL Y-AXIS (bar height)

4 Keys to a Good Graph: TASA 1. Title 2. Axes labeled and in the right place 3. Appropriate scale 4. Accurate representation of data points time

Make Graphs Complete the data and graphs worksheet by plotting the data gathered during the two virtual experiments. Title, Axes, Scale, Accurate If not completed, finish for homework