Part 2 Sections: Using a Series of Experiments cont. Experiment 3.3 Exploring Creation with General Science Week 7 - Mod 3 How to Analyze and Interpret Experiments Part 2 Sections: Using a Series of Experiments cont. Experiment 3.3 Experiment 3.4 Recognizing Experimental Variables When They are NOT Obvious Interpreting the Results of Experiments

Review From Lat Session What is an experimental variable? __________ _________________________________________ When is it good? ___________________________ When is it bad? ____________________________ The motor boats – we were looking for the best _________. What is the CONTROL in an experiment? ________________________________________. What was the “control” in this experiment? 2 2 2

Using a Series of Experiments Perform Exp. 3.3 – “What Does Soap Do To Water? – Part 1” Here we introduce black pepper. Make a chart for the data 1st… tweezers………… tissue…………… gum……………. soap………….. Hypothesis - ___________________________ 3 3

Using a Series of Experiments Perform Exp. 3.4 – “What Does Soap Do To Water? – Part 2” Now we use a needle. Hypothesis - ______________________________ Make a chart for the data 1st… tweezers………… tissue…………… gum……………. soap………….. 4 4

Using a Series of Experiments What did we see in both experiments? We saw the boats move on the surface. We saw the pepper move on the surface. And the needle… When we added soap, this changed something in the water. It changed the _________________________. 5 5

Using a Series of Experiments The Surface Tension can be thought of as a thin film that stretches across the top of all liquids. If not disturbed or broken, it can hold up things that would normally sink. If we had laid the needle on the surface of the water with the thread (try it at home), it would have floated. That is until we added some soap. So what does soap do to the surface tension? 6 6

Using a Series of Experiments The soap actually DECREASED the surface tension of the water. But how does that relate to our experiments? Which boat moved the most? What happened to the pepper? The pepper moved away from the soap. Was it being repelled by the soap? 7 7

Using a Series of Experiments No, the soap decreased the surface tension or film in the middle but didn’t break it near the sides… so the pepper was being PULLED to the sides of the dish. So the soap motor was actually reducing the surface tension for that boat and the film pulled back toward the sides so it looked like the boat was moving on its own when actually it was being pulled toward the sides of the dish due to the change in surface tension. 8 8

Using a Series of Experiments So in the end, what does soap do to surface tension? This is an experimental or direct variable. Name the necessary experimental variables – a.k.a. Direct variables Name the unnecessary exp. variables – a.k.a. Indirect Variables Do “Own Your Own” 3.4 and 3.5. 9 9

Recognizing Experimental Variables When They are NOT Obvious Suppose you are sick – get antibiotics – take some of the pills – feel better – but you don’t take ALL the pills – you get sick again. Back to the doctor you go – she says “_____ _____ ____ ____?” How did she know that a pill would help you? How did she know how many pills to give you? She knows these things because of many experiments or drug trials. 10 10

Recognizing Experimental Variables When They are NOT Obvious When medical scientists come up with a new drug, they have to do many, many experiments before this new drug is approved by the FDA. Usually this involves animal testing, then human volunteers. The human volunteers are usually paid money or are interested in the cure. 11 11

Recognizing Experimental Variables When They are NOT Obvious Lots of experiments are done on human volunteers long before a doctor can prescribe this new drug. There are typical methods used for drug studies… and this is an important point about doing experiments. You must go step by step; non-species trials, then animal trials, then finally human volunteers. 12

Recognizing Experimental Variables When They are NOT Obvious Let’s read through Handout 10.18.10 – 1 “Designing Good Experiments” Do “On Your Own” 3.6 and 3.7 13

Interpreting the Results of Experiments So… you now can design an experiment. You can recognize and use direct & indirect variables. And you can “control” for variables that might affect your experiment. Now let’s look at some results from an ocean-based experiment. Recall Experiment 3.1 – The Floating Egg… we mixed lots of salt with water – salt water. Did the salt disappear – not really, it _______. 14

Interpreting the Results of Experiments Many things dissolve in water including gases. For example – soda pop – CO2 dissolved in sugar water. Fish live off the oxygen (O2) dissolved in the water – no O2, no live fish. Fish have ____ which grab the dissolved oxygen and allow the fish to breath in the O2. Not enough O2 in the water and the fish suffocate. 15

Interpreting the Results of Experiments At home – fish tank – air pump – puts O2 into the water. This is amazing to think about – we all need O2, we just get it in different ways. Imagine if you could breath under water without any breathing apparatus. Look at Figure 1.1 (3.2 corrected) – Dissolved O2 at Varying Levels of the Bering Sea. Very important to understand – “X” axis – depth of the water – “Y” axis is amount of O2 in the ocean water. 16

Interpreting the Results of Experiments The higher the dot is on the graph, the more dissolved O2 is in the water. The farther to the right the dot is on the graph, the deeper the measurement was taken. At depths less than 400 meters, the amount of dissolved O2 is relatively high. It is highest at 100 meters. Between 400-500 meters, the O2 decreases very quickly. Then it starts rising very slowly. Do “On Your Own” 3.8, 3.9, and 3.10. 17

For next time… Turn in On Your Owns 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, and 3.10. Write up Experiment 3.3 Experiment 3.4 – did it work? Take your Module 3 Test at home – your Dad or Mom grades it. Next Week: read ½ of Module 4. 18 18