Experimental Flaws Revealed Through Technology PETE&C 2009 Matt Kohler

1. Experimental Flaws Revealed Through TechnologyPETE&C2009Matt Kohler Gateway High School Science Department Chemistry/Physics mkohler@gatewayk12.org

2. PA Standards in this Lesson Reading, Writing, Speaking and Listening Science and Technology 1.5.11 A 1.5.11 B 1.5.11 C 1.5.11 F 1.6.11 A 1.6.11 D 1.6.11 E 1.6.11 F 1.8.11 C 3.2.10 B 3.2.10 C 3.4.10 A 3.4.10 B 3.7.10 B 3.7.10 D 3.7.10 E

3. Technology Involved • CFF Laptops • CFF Digital Projector • Vernier Lab Pros • Vernier Temperature Probes • LoggerPro (Vernier Software for data collection) • Microsoft Word • Microsoft PowerPoint • Moodle

4. Overview of Lesson • 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

5. Lesson (cont) • 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 VenierLabPros, Vernier temperature probes and CFF laptops

6. 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

7. Science Concepts • 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)

8. Demonstration • 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

9. What did students find? • 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

10. Other Interesting Finds… • 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

11. Implications for Teaching • 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

12. Incorporating the technology… • 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

13. Questions? Feel free to email: mkohler@gatewayk12.org