# Gas Density

For the first lesson of Chapter 11, students worked with dry ice and watched a couple of teacher demonstrations involving dry ice.  To begin class, students quickly assembled into groups of 2-3 and transferred a small amount of dry ice into a deflated plastic bag which they sealed closed.  Students recorded the mass of the dry ice added to the bag, then measured the volume of the bag after the dry ice finished sublimating in order to calculate the density of carbon dioxide gas.

While waiting for the dry ice to sublimate, students hypothesized about what they might observe when water ice and dry ice were heated on a hot plate, and also what would happen when water and dry ice were added to liquid water or vegetable oil (pictured below).

Students then observed the outcomes and recorded their observations on the Lesson 56 Worksheet.  Students also recorded the definitions of sublimation and evaporation, both of which are included in the Lesson 56 PowerPoint.  For homework, students were assigned problems 1-10 from Lesson 56 in the textbook.

Note: For students who missed class due to testing today, please watch the videos below as a substitute for participating in the lab.

# Introduction Writing

In addition to efficiently observing seed germination, making measurements of roots and shoots, and recording all the data in Google Sheets, students should browse through the following resources:

Students should note whether the seeds used in their own experiment are dicots or monocots, and be prepared to explain the difference between the two.  Students should take careful notes about the optimal conditions for seed germination, focusing on the biology of the seed and especially the sources of energy the seed uses to germinate.

Next, students should work together to write the Introduction paragraph of their lab report.  The Introduction should include the following:

• State (in a sentence or two) the scientific concept the lab is about.  Hint: germination!
• Describe what you know about germination and how the lab is investigating the process of germination.  Include a discussion about how the energy used for germination is different from the energy used for plant growth.
• State the hypothesis in if/then/because format for the experiment and then explain:
• why this particular hypothesis was selected