Electronegativity and Polarity

We began class with students receiving copies of their progress reports and a copy of the Lesson 43 Worksheet and accompanying cartoon.  After reading through the cartoon, we briefly worked through parts of the Lesson 43 PowerPoint and students received a copy of the periodic table that includes the electronegativity values for each element.

We then investigated four different molecules and discussed the connection between molecule geometry, atomic composition, and how to calculate the difference in electronegativity between two atoms.  Students learned that non-polar covalent bonds have a difference in electronegativity of 0.5 or less.  An electronegativity difference greater than 2.1 results in an ionic bond.  Values between 0.5-2.1 result in polar covalent bonds.

For more on dipole moment, check out the Khan Academy video below:


For homework, students are assigned questions 1-4 on page 226.

Strawberry DNA Lab Report

As we enter our final week of Unit 4, students received a progress report, their graded quiz from Friday, and a copy of the Strawberry DNA Extraction Lab Checklist.

Students with a D or F we told that in order to qualify for an in-progress (IP) grade at the end of the semester, they need to take their progress report home, explain it to their parent/guardian, craft a plan to pass biology, and then bring the progress report back signed and with a written plan.

We briefly reviewed the quiz and most students achieved a perfect score, solving the RNA and amino acid sequences perfectly.  Because there were two versions of the exam, with table partners receiving different copies, it was immediately evident if any copying occurred.  Students were again reminded about the importance of academic honesty, and students who copied received a score of zero.

Next, we reviewed the lab checklist and then watched the video below to provide students with the academic learning required to explain the role of soap, salt, and isopropyl alcohol in the lab.

Finally, students who completed the New Genetics assignment were allowed to use class computers to begin writing their lab reports.  Students who have not yet completed the assignment had class time to do that work.  Students were reminded that the lab report is due Thursday and we have an exam Friday.