Comparing Water Ice and Dry Ice
Objectives: After completing the lesson, students will be able to:
make objective observations and comparisons;
make observations without making prior assumptions.
Key Question: "How does water ice compare to dry ice?"
Overview: Students are given an opportunity to examine the behavior of water ice and dry ice, and write down what they observe. The teacher then leads a demonstration in which energy, in the form of heat, is added to both water ice and dry ice. Again, students are to write down their observations into their scientific journals. Finally, the session ends with an introduction to the phrase "nullius in verba," which loosely translates into "don't take anybody's word for it." The ensuing discussion focuses on a key theme of doing science: explanations of how the world works must be based on objective observations that can be repeated by others, not on prior assumptions.
Time Required: 45-60 minutes (1 class session).
for the class
insulated storage container
leather work glove
flat piece of metal
for each 3-4 student group
plastic cup with regular ice cube
plastic cup with dry ice
"As If Seeing It for the First Time,"
"Comparing Substances," and "Adding Energy" student
handouts (pp. 34-36 in Dry
Procedure: see pp. 26-33 in Dry Ice.
Assessment: student responses to the Scientific Journal pages, "As If Seeing It for the First Time," "Comparing Substances," and "Adding Energy."
Students should be given an opportunity to complete and edit their responses to the three Scientific Journal pages, "As If Seeing It for the First Time," "Comparing Substances," and "Adding Energy." As an extension, students can be asked to contemplate the relationship between the expression "nullius in verba" and their observations during this lesson. Students can also be asked to propose explanations for the differences in behaviors they observed between dry ice and water ice.
OUSD Science Content Standards (State of California Science Content Standards):
1-d; 1-e (7.1-c; 7.1-d)
Barber, Jacqueline, Kevin Beals, and Lincoln Bergman. Dry Ice Investigations: Teacher's Guide. Berkeley, CA.: Lawrence Hall of Science, University of California, Berkeley, 1999, pp. 7-9, and 26-36.
Notes: This is the first lesson that requires the use of dry ice. It is necessary, before beginning this lesson, that students understand the importance of working as a team in a safe manner. It is a good idea, therefore, to read the information about obtaining and handling dry ice in a safe manner, found on pp. 7-9 in Dry Ice. Two sources for obtaining dry ice in Oakland are:
A-1 Arco AM/PM Gas Station
889 W. Grand Avenue (at Market Street)
hours: open 24 hours daily
Praxair Dry Ice
1171 Ocean Avenue (1 block west of San Pablo Avenue, between 64th and 65th street)
hours: M-F 8 am-5 pm
Obviously, there can be some hassles with obtaining dry ice at a given school site. One cannot underestimate the excitement and interest level demonstrated by 6th grade students when doing dry ice experiments. However, if obtaining and working with dry ice proves to be too insurmountable a barrier at a given site, it is possible to meet the curriculum goals for this section of Unit 1 by substituting experiments outlined in the Oobleck and/or Bubbleology GEMS guides (available through the Lawrence Hall of Science) for the lessons that require dry ice outlined here.