What does the image of the slide below signify?

The notes below taken by your colleague(s) are being made available to you as a courtesy. They are published here on an "as is" basis (meaning I have not reviewed them); therefore, you should use them with discretion to supplement your own notes. Yes. Note-takers can also get the wrong end of the stick! If you find these notes useful please be sure to thank the note-takers in person. Remember: gratitude never goes amiss! <-- what does this sentence mean?

Monday-August 27

Wednesday-August 29

Monday-September 3 (school break--Labor Day)

September 5

September 10

September 12

September 17 (gb)

September 19 -- Test day

September 24  September 24 (al)

September 26

October 1 October 1 (al)

October 3 October 3 (al)

October 8 -- Paper

October 10

October 15

October 17 (al)

October 22   October 22 (al)

October 24 

October 29  October 29 (al)  

October 31 (al) 

November 5

November 7--Test day

November 12

November 14

November 19

November 21--Break

November 26

November 28

Gratitude never
                goes amiss