Category: My Classroom Material

Scientific Laws

 

Scientific Laws, Hypotheses, and Theories

 

 

Scientific Theory versus “Just a theory” Layman’s term:

In layman’s terms, if something is said to be “just a theory,” it usually means that it is a mere guess, or is unproved. It might even lack credibility. But in scientific terms, a theory implies that something has been proven and is generally accepted as being true.

Scientific Meanings:

SCIENTIFIC LAW: This is a statement of fact meant to describe, in concise terms, an action or set of actions. It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true. Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.  Some scientific laws, or laws of nature, include the law of gravity, Newton’s laws of motion, the laws of thermodynamics, Boyle’s law of gases, the law of conservation of mass and energy, and Hook’s law of elasticity.

HYPOTHESIS: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation.

THEORY: A theory is more like a scientific law than a hypothesis. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. One scientist cannot create a theory; he can only create a hypothesis. Theories may be expanded or modified with further scientific evidence.

Development of a Simple Theory by the Scientific Method:

  • Start with an observation that evokes a question: Broth spoils when I leave it out for a couple of days. Why?
  • Using logic and previous knowledge, state a possible answer, called a Hypothesis: Tiny organisms floating in the air must fall into the broth and start reproducing.
  • Perform an experiment or Test: After boiling some broth, I divide it into two containers, one covered and one not covered. I place them on the table for two days and see if one spoils. Only the uncovered broth spoiled.
  • Then publish your findings in a peer-reviewed journal. Publication: “Only broth that is exposed to the air after two days tended to spoil. The covered specimen did not.”
  • Other scientists read about your experiment and try to duplicate it. Verification: Every scientist who tries your experiment comes up with the same results. So they try other methods to make sure your experiment was measuring what it was supposed to. Again, they get the same results every time.
  • In time, and if experiments continue to support your hypothesis, it becomes a Theory: Microorganisms from the air cause broth to spoil.

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Rubric Chimpanzee Webquest

 

 

Chimpanzee Webquest

 

Group # _____     Students:
Oral Presentation Rubric Possible Points Self-Assessment Teacher Assessment
Complete Venn diagram with unique adaptations listed at bottom. 25
PowerPoint Presentation well-designed and with 15 slides 25
Presentation was well planned and coherent. (Evidence of rehearsal) 10
Poster board  (helpful, neat) 10
Teamwork:  Every member of group played a role 10
Presentation shows evidence of research on Chimpanzees (good understanding of similarities and differences) 10
Communication Skills (eye contact, posture, clear voice, appropriate volume, transitions between speakers smooth, and all members presented) 10
Total Possible Points 100

Scientific Method activity

Scientific Method “I’m All Thumbs”
Introduction:
What makes a “Class Champion” thumb wrestler? Does thumb diameter, length, or wrist diameter have an effect on the overall chances of winning a thumb wrestling match? In this investigation we will develop a hypothesis based on physical data collected from our classmates. We will then test this hypothesis by conducting a thumb wrestling tournament to determine an overall “Class Champion”.

Materials:
Metric ruler, metric tape measure (see bottom of lab), scissors, string, calculator

Objectives:

  • Students will take and record accurate measurements of their wrist, and their thumb’s circumference and length.
  • Students will analyze the data collected and determine if their hypothesis is correct.
  • Correctly line graph the collected data.
  • Learn the rules of thumb wrestling.
  • Conduct a thumb wrestling tournament.

Procedures:

  • Choose a partner and perform the following measurements using the metric tape measure found at the bottom of this lab. Then have your partner perform them on you.
  • Measure the circumference of the thumb, in centimeters, at its widest point. Record this data on the following line ___________cm. and on the table on the chalk board.
  • Measure the length of the thumb, using the metric ruler in centimeters, from its tip to the end of its second joint. Record this data on the following line ___________cm. and on the table on the chalk board.
  • Measure the circumference of the wrist over the ulnar knob, in centimeters, and record this data on the following line ____________ and on the table on the chalk board.
  • Copy the data, on the board, on to the table in the results section of the lab.
  • The class will form and record a hypothesis based on the collected data.
  • The Hypothesis:
    ______________________________________________________________

        ______________________________________________________________

  • Rules of thumb wrestling: Two players grasp hands shown in the illustration; they touch thumbs to the opposite sides of the other person’s hand three times, then come out wrestling. The object, of course, is to hold the other person’s thumb down, for a count of three, using only your thumb.

 

  • Boys will wrestle boys and girls will wrestle girls.
  • A tournament schedule will be set up to match opponents.
  • After the completion, a champion will be declared in both categories, (male and female).

Results:
Complete the following data table:

 

Student Name
Gender (M / F)
Thumb Circumference in cm
Thumb Length in cm
Wrist circumference in cm
Record
( won/ lost)
Optional
1.aaaaaaaaaaaaaaaaa
M / F
2.aaaaaaaaaaaaaaaa
M / F
3.aaaaaaaaaaaaaaaa
M / F
4.aaaaaaaaaaaaaaaa
M / F
5.aaaaaaaaaaaaaaaa
M / F
6.aaaaaaaaaaaaaaaa
M / F
7.aaaaaaaaaaaaaaaa
M / F
8.aaaaaaaaaaaaaaaa
M / F
9.aaaaaaaaaaaaaaaa
M / F
10.aaaaaaaaaaaaaaaa
M / F
11.aaaaaaaaaaaaaaaa
M / F
12.aaaaaaaaaaaaaaaa
M / F
13.aaaaaaaaaaaaaaaa
M / F
14.aaaaaaaaaaaaaaaa
M / F
15.aaaaaaaaaaaaaaaa
M / F
16.aaaaaaaaaaaaaaaa
M / F
17.aaaaaaaaaaaaaaaa
M / F
18.aaaaaaaaaaaaaaaa
M / F
19.aaaaaaaaaaaaaaaa
M / F
20.aaaaaaaaaaaaaaaa
M / F
21.aaaaaaaaaaaaaaaa
M / F
22.aaaaaaaaaaaaaaaa
M / F
23.aaaaaaaaaaaaaaaa
M / F
24.aaaaaaaaaaaaaaaa
M / F

 

Graph Title: ____________________________________________________________


Analysis and Conclusion :

1. Restate your hypothesis: __________________________________________________

2. Which students won? (male) __________________________ and (female)_____________________

3. What were their measurements:

male: thumb circumference: ____________, thumb length ______________, and wrist circumference ______________;

female: thumb circumference:__________, thumb length _________, and wrist circumference ______________.

4. What was the mean thumb circumference of the class? _____________cm

5. What was the mean wrist circumference of the class? ______________cm

6. Did all those with larger measurements win their matches? ____________.

7. Was you hypothesis correct? ______________.

8. If not, explain what was different. 

_____________________________________________________

_____________________________________________________

_____________________________________________________

9. What is the independent variable? _____________________________________

10. What is the dependent variable? ______________________________________

11. List the controlled variables in this experiment. 

         __________________________________________________

__________________________________________________       

11. Would this be considered a controlled experiment? ____________.

12. Explain your answer.

_____________________________________________________

_____________________________________________________

_____________________________________________________

Here is a sample tournament grid : Cut and turn sideways.

_______________________________________________________________________

_______________________________________________________________________

 

Cut and use.

________________________________________________________________________

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Safety Guidelines

Safety Guidelines
All Materials © Cmassengale

 

  1. Safety goggles/glasses & aprons must be worn at all times in the laboratory.
  2. Tie back long hair & secure lose clothing.  
  3. No horseplay is allowed in the lab.
  4. No food or drink is allowed in the laboratory.  
  5. Practice good “housekeeping” techniques.  Return items to proper places in good condition.  Avoid cluttering your work area.
  6. Never use chemicals from unlabeled containers.  Check each label before dispensing a chemical, & do not return a chemical to a bottle without the teacher’s permission.
  7. Unless told otherwise, treat all chemicals as poisonous or corrosive.  Wash hands immediately with plenty of water if chemical gets on them and always wash your hands before leaving lab.  
  8. No unauthorized lab work may be done, & a teacher must be present to do lab work.  
  9. Read & study each lab assignment before coming to lab.  Pay attention to safety notes in the lab manual and from the instructor.  Some common lab concerns:
    * Never pipette by mouth
    * Never use chipped or cracked glassware
    * Do not heat a closed system
    * Do not point heated containers at yourself or another person
    * Use a fume hood for noxious fumes
    * Place heated glass on wire gauze until cool
    * Do not use flammable material near open flame
    * Wear gloves when dispensing irritating chemicals
    * Dilute concentrated acids by adding acid to water
    * Turn off burners and water faucets when not in use & before leaving lab
    * Only heat glassware marked Kimex or Pyrex
    * Use glycerin and a twisting motion to insert glass tubing into stoppers
    * Use tongs, test tube holders, or heat-resistant gloves to handle hot glassware
    * Use pins to secure dissecting organisms to the dissecting tray before cutting with a scalpel
    * Wash hands before and after dissecting and keep hands away from your face
  10. Report all accidents immediately to the teacher.
  11. Know the location and proper use of all safety equipment in the lab.
  12. Know where all exits are from the lab.

 
PRINT SAFETY RULES & LAB CONTRACT HOME      PRINT SAFETY WORKSHEET

 

Scientific Method puzzle

Scientific Method

Find each term and then define it on the back of the paper.

 

 

Y N B E L F U N I J M H T N M
H O E N B G W N C G W N Q S Y
A I R X H Y P O T H E S I S C
C T E A P L K J V D V L Y R O
H A A L U E Q G N I O F E C N
A V X D B P R E X R S P G F C
R R C E B A P I T O E H S F L
T E G T R E I N M A H T I K U
I S E S D R O R T E A Y S A S
E B K N V C O A A B N Q Y V I
I O I Q T V B R L V K T L P O
S X Q R F L L E S H J S A P N
B I T N E D N E P E D X N V B
Q O N I Y K Z H E L Q Z A J P
T E S T I N G H P A R G N R O

 

 

 

ANALYSIS CHART CONCLUSION
CONTROL DATA DEPENDENT
ERRORS EXPERIMENT GRAPH
HYPOTHESIS INDEPENDENT OBSERVATION
REPEATABLE TABLE TESTING
VARIABLE

 

 

 

 

Solution