Universal approach to problem-solving in science!! The Scientific Method Universal approach to problem-solving in science!!

1. Ask a Question?? (State the Problem) – based on observations Will the caffeine in coffee prevent mold growth? Does temperature affect the rate of diffusion? What wavelength of light do plants photosynthesize the best under? What brand of diapers is the most absorbent?

2. Gather Background Information Go to library to find out what other similar questions scientists have asked and what conclusions they have come to.

3. Hypothesis A testable explanation for a question or problem. “an educated guess” “If plants reflect green light, then the rate of photosynthesis will decrease under green wavelengths of light."

4. Experimentation Procedure that tests the hypothesis Controlled Experiment – has 2 groups: Control group: all conditions are kept the same for comparison purposes Experimental group: “test” group(s), only a single factor is changed = INDEPENDENT VARIABLE. The change that results is called the DEPENDENT VARIABLE.

Let’s Practice…. A team of students hypothesized that seeds would germinate faster at warmer temperatures. They divided 50 radish seeds into 2 identical pots and held all conditions – light, water, fertilizer- the same except for temperature. One pot was kept at 18oC and the other at 25oC. They measured the number of seeds that germinated over 10 days. Independent Variable ?? Did you say temperature? Dependent Variable?? Did you say # of seeds germinated?

Some more? Independent Variable ? Dependent Variable ? Control Group ? A scientist hypothesized that tobacco plants would grow better with fertilizer. He took identical seeds, put in identical pots, watered the same amount, gave them the same amount of light, etc. The only thing different between the two plants was that one had fertilizer added to the soil and the other did not. He could then measure their growth. Independent Variable ? fertilizer Dependent Variable ? Rate of growth Control Group ? One without fertilizer Experimental Group ? One with fertilizer

5. Collect Data Use your 5 senses to make OBSERVATIONS: a. Quantitative = # ( 5 cm.) b. Qualitative = subjective (tan in color) Usually recorded in tables, graphs, charts, etc.

6. Analyze data & draw conclusion! Report & publish results… when a scientist’s data supports the hypothesis & it is supported by additional experiments….becomes a THEORY. For example, the cell theory. If hypothesis is not supported…reject or revise, ask new questions and test again.