gateway high school science department chemistry/physics [email protected]
TRANSCRIPT
Experimental Flaws Revealed Through
Technology
PETE&C2009
Matt Kohler
Gateway High School Science DepartmentChemistry/Physics
PA Standards in this Lesson
1.5.11 A1.5.11 B1.5.11 C1.5.11 F1.6.11 A1.6.11 D1.6.11 E1.6.11 F1.8.11 C
3.2.10 B3.2.10 C3.4.10 A3.4.10 B3.7.10 B3.7.10 D3.7.10 E
Reading, Writing, Speaking and Listening Science and Technology
CFF Laptops CFF Digital Projector Vernier Lab Pros Vernier Temperature Probes LoggerPro (Vernier Software for data
collection) Microsoft Word Microsoft PowerPoint Moodle
Technology Involved
Before Experiment:◦Students in an academic chemistry class
are challenged to be able to design and carry out an experiment to determine the effects of adding salt to ice on the freezing point water and whether or not the changing of the freezing point is a colligative property
Overview of Lesson
During Experiment:◦Lab groups must jigsaw in order to divide
up all of the salt and ice ratios in a timely manner
◦Students measure temperatures using Venier LabPros, Vernier temperature probes and CFF laptops
Lesson (cont)
After Experiment:◦Individual lab groups format LoggerPro
graphs into Microsoft Word documents and post results to online forum (at Gateway School District this is Moodle)
◦Each group presents a brief PowerPoint that outlines their results and preliminary conclusions
◦Each lab group retrieves all other groups results in order to write complete the required lab report
Lesson (cont)
Chemical Kinetics◦ How molecules translate
Colligative Property◦ Property that depends on the concentration of solute
molecules or ions in a solution but not on the chemical identity of the solute
Systematic Error◦ Error that arises from a flaw in equipment or the
design of an experiment Random Error
◦ Error that arises from the effects of uncontrolled (and may be uncontrollable) variables in the measurement
(Ebbing and Gammon 2005)(Harris 2003)
Science Concepts
Salts (same # molecules for each):◦ Sodium chloride (NaCl)
5.8 g◦ Calcium chloride (CaCl2)
11.1 g◦ Ammonium chloride (NH4Cl)
5.4 g
Coffee cups and scoopula
Water (ice)◦ 100 g
Mixing vs. Not Mixing
Demonstration
Mixing vs. Not Mixing plays a big role in gathering accurate data
Insulating the system also plays a role◦ One vs. multiple coffee cups◦ Lids?
Time is a factor◦ An initial trial run is needed to establish an
adequate time frame
What did students find?
Many students predict that the freezing point of water should increase when the salt is added◦ Does this make sense?
Many students in each class perceived (after the experiment) that simply conducting more trials would improve results◦ Only addresses random error
Some students immediately recognize that each groups’ procedures must be adjusted to the same length and involve stirring to eliminate systematic error
Other Interesting Finds…
The National and PA Science Standards state the need for understanding the nature of science
Science education needs to stress both content AND the process of science in order to promote scientific literacy◦ Students come from various elementary and middle
school settings (and sometimes other districts)◦ Students usually take chemistry after Earth and space
science and biology◦ The nature of science needs to be stressed in all
levels of science education
Implications for Teaching
The technology is easy to use and not very time consuming
Don’t feel overwhelmed! The Vernier technology can be used in
numerous other variations and applications◦Chemistry, Physics, Biology, and others
Vernier equipment is designed to mix and match
Vernier equipment is reasonably priced and basic startup equipment could be obtained by mini grants
Forum software can be obtained for the entire school
Incorporating the technology…
