What is it? A tool used by scientists to gather information about scientific observations and questions.

The Steps… Observation Problem/Question Research Hypothesis Materials Methods Results Conclusion

Our Example Bubble Gum!

Observation Scientist notices something about the world around them This observation will begin the process and lead to the next step Bubble gum changes as you chew it

Problem/Question The scientist poses a question about his/her observation How? What? When? Where? Why? Who? How does the weight of bubble gum change as you chew it?

Research Scientists will gather as much background information about their question as possible to create and educated hypothesis. Must be peer reviewed! Gain knowledge to develop a “good” experiment Must be put into your OWN words!!! We did not do this in our lab NOTE – Small, classroom experiments will often times not include this step.

Hypothesis A hypothesis is a tentative statement that proposes a possible explanation to some phenomenon or event (or our question(s)). Testable, testable, testable! May contain prediction The bubble gum’s weight will decrease by 20%.

But Were We… Never say Right or Wrong!!! A hypothesis is never Right or Wrong. A hypothesis is either supported or not supported. Hypothesis Theory Law Right or Wrong can be used here, and only here!!!

Starter Name the steps of the scientific method in order. What makes a good hypothesis? What are the two groups when creating an experiment? What are the 3 types of variables?

______ A scientist goes to the library and reads a number of articles about the physical properties of solutions. ______ A scientist goes to the laboratory and does the following: 1. Fills each of two beakers with 1 liter of fresh water. 2. Dissolves 35 grams of table salt in one of the beakers. 3. Places both beakers in a freezer at a temperature of -1°C. 4. Leaves the beakers in the freezer for 24 hours. ______ A scientist wants to find out why seawater freezes at a lower temperature than fresh water. ______ After 24 hours a scientist examines both beakers. The salt water is liquid and the fresh water is frozen. ______ A scientist who lives in Rhode Island near the ocean shore notices that the pond in his yard was freezing earlier in the winter than the ocean shore. ______ A scientist suggests “Ocean water freezes at a higher temperature than fresh water does.” ______ A scientist gathers and uses: - two beakers - 1 liter of fresh water - salt - a freezer ______ A scientist discusses and writes down what errors he/she think occurred in the experiment and what they would do different next time.

Materials The materials used by a scientist that are necessary to test the hypothesis. The materials are listed clearly and accurately to help with recreation of the experiment. Bubble Gum Paper towel Scale Clock (with second hand)

Methods The methods are a description of how to perform the experiment in the exact way the scientist did. They are detailed so that any one of your peers could read and repeat the exact experiment. They are numbered and in complete sentences. You were able to read and repeat the experiment I had conducted with the Bubble Gum.

Variables Independent - What is changed - X-Axis Dependant - What is measured - Y-Axis

Your turn – Identify and write down the dependent and independent variables in the following examples: 1. Bean plants are given varying amounts of water and the height is measured after 2 weeks. 2. Guinea pigs are kept at different temperatures for 6 weeks. Percent weight gain is recorded. 3. The number of sea lions is calculated for a coastal area before and after an oil spill. 4. Light absorption by a pigment is measured for red, blue and yellow light. 5. Groups of seeds are soaked in salt solutions of different concentrations and germination is counted for each group. 6. An investigator hypothesizes that the adult weight of a dog is higher when it has fewer siblings

Standardized Any variables besides the dependent and independent variables that may affect your experiment. The investigator must try and keep these the same throughout the experiment. Possible always? Examples?

Your turn. Go back to the 1 st dependent and independent variable problem and list all standardized variables you can think of when growing bean plants.

Control A control is used in an many scientific experiments It is what scientists use to compare their results to Used to measure change

Your turn Give an appropriate control for each of the following examples. Also identify the dependent and independent: 1. The effect of the light intensity of photosynthesis is measured by collecting oxygen produced by a plant. 2. The effect of NutraSweet sweetener on tumor development on lab rats is investigated. 3. Subjects are given squares of paper that have been soaked in a bitter-tasting chemical. The investigator records whether each person can taste the chemical. 4. A solution is made up to stimulate stomach acid at pH 2. Maalax antacid is added to the solution in small amounts and pH is measured after each.

Results Raw Data! Graphs and Tables There is no interpretation of the data here!!! (No explanation of ‘why?’) Tables and graphs are labeled and titled. The weight of the gum at each time interval in our table.

Conclusion Scientists interpret the data and draw conclusions from it. The hypothesis is supported or not supported here. Possible errors are discussed here. What was learned from the experiment is described here. You should have written your short conclusions about what you discovered.

What else goes into making a great experiment? Replication Repeating the exact experiment a number of times to increase confidence in the results. Statistically sound – eliminates answers due to just random chance The greater number of repetitions, the greater the confidence. IN

What goes along with replication? Sample size The number of samples used in the experiment. As large as possible At least 30 TEM An increase in sample size also increases our confidence in the results of the experiment

Graphing Title Tells what the graph is about X-Axis Independent variable What is changed! (ex: time, temperature, depth, etc.) Y-Axis Dependant variable What is being measured Scales Must include all data points