Lab Safety Cartoon Questions 1. List 3 unsafe activities shown in the illustration and explain why each is unsafe. 2. List 3 correct lab procedures depicted in the illustration. 3. What should Bob do after the accident? 4. What should Sue have done to avoid an accident? 5. Compare Luke and Duke's lab techniques. Who is following the rules? 6. What are three things shown in the lab that should not be there? 7. Compare Joe and Carl's lab techniques. Who is doing it the correct way? 8. What will happen to Ray and Tim when the teacher catches them? 9. List three items in the illustration that are there for the safety of the students in the lab. 10. What is Betty doing wrong?
WARM UP 1. You have accidentally broken a test tube and spilled a chemical on the table. What should you do? 2. True or False: You should wear safety goggles during every science block.
OHEC • • Observe Hypothesize Experiment Conclude
Observation A note made by studying something using sight, sound, touch, smell and taste • Will all popcorn kernels pop if bagged popcorn is stored in a cabinet or refrigerator? • Will warm water or cold water help a plant grow faster? • Does bar soap clean your hands better than sanitizing solution? • Will more ants eat butter or margarine? • Does salted water boil faster than unsalted water?
Inference • Inference is just a big word that means a conclusion or judgement. If you infer that something has happened, you do not see, hear, feel, smell, or taste the actual event. But from what you know, it makes sense to think that it has happened.
Hypothesis A scientific guess as to the outcome of an experiment • If bagged popcorn is stored in a refrigerator then all the kernels will pop. • If a plant is given warm water then it will grow faster than a plant given cold water. • If you clean your hands with sanitizing solution then your hands will not be cleaner than if you used liquid soap. • If ants are fed butter then they will not eat margarine. • If salt is added to water then the water will not boil faster.
How to make a hypothesis If _________then ________ independent variable dependent variable The variable that is changed by the experimenter What’s different? The variable that changes as a result of the independent variable What did they measure?
Experiment • Steps used to conduct an investigation • One bagged popcorn of the same brand is placed in the refrigerator for 24 hours. • Two of the same type plant were watered. One plant is given water at 75 degrees Celsius and one plant is given water at 15 degrees Celsius. • An individual has one hand cleaned with sanitizing solution and the other hand cleaned with liquid soap. The sanitized hand is allowed to dry while the other hand is washed for twenty seconds and then rinsed. • To determine which lipid ants would eat, ants from the same colony were given ½ tablespoon of margarine and ½ tablespoon of butter.
Experimental vs. Control Experimental Group subjected to the independent variable Ex: Cold water for plant or warm water for plant Control Group All variables kept constant. Used for comparison during the experiment Ex: Room temperature water for plant
Conculsion Statement that explains the results of the experiment • Popcorn stored in the refrigerator popped better than popcorn stored in the cabinet; was hypothesis proven or disproven. • *Plants given warm water grew better than plants given cold water; was hypothesis proven or disproven • *Hands cleaned with liquid soap have fewer germs than hands cleaned with sanitizing solution; was hypothesis proven or disproven • *More ants ate the butter than margarine; was hypothesis proven or disproven • *The salted water boiled faster than the unsalted water; was hypothesis proven or disproven
Try it! In 1928, Sir Alexander Fleming was studying a bacteria growing in culture dishes. He notices a mold called Penicillium was also growing in some of the dishes. A clear area existed around the mold because all the bacteria that had grown in this area had died. Fleming hypothesized that the mold must be producing a chemical that killed the bacteria. He decided to isolate this substance and test it to see if it would kill bacteria. After he grew the mold in a nutrient broth, he removed the mold and added the broth to a culture of bacteria. The bacteria died. This is how the antibiotic Penicillin was discovered. 1. What was the problem? 2. What was the hypothesis 3. What was the conclusion of the experiment.
Lab Tools • • • Scalpel Forceps Beaker Hot plate Microscope Petri dish Pipette Test tube Slide cover • • Slide Probe Graduated cylinder Goggles Erlenmeyer flask Test tube rack Tongs