Wednesday, August 29, 2007

First Day of School: Mini-Lesson on Calculating a Tip

The first day of school was, as always, a thrilling, frightening, and incredibly confusing marathon day. With over 2,000 students likely to fill up a building designed for 1,600 over the next week, it's not likely to get any less hectic any time soon. That being said, the honeymoon is still going strong in my classroom, even as I eschewed established norms and actually began teaching right on the first day.

I didn't do any icebreakers or team-building activity for 3 reasons:
  1. My students already had to be subjected to that from almost every other teacher.
  2. Most of the activities you can find online, even the ones that claim to be designed for high school students, are clearly designed for lower grades (or make the correct assumption that freshmen are scared out of their minds and will do whatever you tell them on the first day). A good sample can be found in "Fun Activities Get the School Year Off to a Good Start!" on Education World.
  3. I don't like them.
I spent a lot of time talking, to the point that my throat was ripped to shreds by the end of the day. I talked about all the important stuff from my first day materials. I read quotes from end-of-year surveys from last year, where my students answered the question: "If you knew someone in the 8th grade who was going to be in this class next year, what would you tell them?" The responses were insightful and inspirational--at least to me, anyway. I felt that anything I could try to tell them about myself would be better received coming from students instead.

I am one of those teachers that has a seating chart on the first day (desks are numbered and a numbered list was on the overhead), not because I care about that sort of thing, but because I desperately want to learn their names and I've found no better way. I had fun with it--I seated them reverse-alphabetically from front to back. The seating chart is of course also great for setting the tone--they walked in, found their assigned seat and had work to do immediately (the student survey).

I gave a whirlwind tour of my highly organized room, a space designed to both keep me sane and reinforce the mostly-business tone I was trying to establish:
  • I use those interlocking wire storage cubes to hold their notebooks, and have numerous crates of hanging files for various reasons.
  • There's a word wall, an elementary school strategy that our high school has adopted, thus forcing me to be very creative in coming up with effective uses.
  • The whiteboard is sectioned off with painter's tape demarcating my "Kickoff" (commonly known as the "Do Now" in TFA vernacular), agenda, TEKS objectives, and homework (usually blank space).
  • Weekly grades are posted on a bulletin board by ID number and rank, as well as extra credit opportunities for the six week grading period, to encourage them to take responsibility for their academics
  • Students of the Week (click for qualifications) are also posted, one for each class period. The only reward usually associated with it is the satisfaction of a job well done, and the occasional dropping of the lowest grade.
  • And, of course, our fledgling classroom library (books, magazines and newspapers), there for students to enjoy (when they're done with their work).
Afterwards, I told them they were going to do the one thing they didn't expect on the first day of school: they were going to learn something. Moreover, they were going to learn something they could use in real life and astound their friends and family with their amazing mathematical ability.

I presented a mini-lesson on calculating a restaurant tip in their heads:
  1. Start with a discussion of why its customary to tip waitstaff (typically they make their living off of tips, because they're often paid well below minimum wage), and what's considered a normal tip (15%) and a good tip (20% or above).
  2. Let's say we have a $25.00 bill, and we want to leave a 20% tip. Instead of pulling out a cellphone to use its calculator, we break the problem into a simpler step first: what's 10% of $25.00?
  3. Ask them if they know what 10% looks like as a decimal (0.1), and what happens when you multiply anything by 0.1. This is the central trick; the number doesn't really change. The decimal moves one place to the left, so $25.00 becomes $2.50.
  4. Now we know 10% is $2.50. Ask, "What do we have to do to the $2.50 to make it into 20%?" They might say, "Double it!" Make sure to ask why, so they're forced to explain that since 10 is half of 20, they have to add another 10% or $2.50 (or another similar explanation).
  5. Make sure to have them total the bill with tip ($30).
  6. Repeat step 4, but for a 15% tip instead. Ask them what has to be done to get that extra 5% (finding half of $2.50), and what the new total would be ($25.00 + $2.50 + $1.25 = $28.75).
I joked that they could tell whoever was going to pay to let them figure the tip and then have them check it on the cellphone calculator. For certain periods I extended this lesson into how to estimate how much money you could save on a sale, referring to back-to-school sales as a current real-world connection. I did an example of a $125.00 item that was 60% or 25% off, and we used the 10% trick to estimate it quickly and easily.

I enjoyed actually teaching something, and I think the mere gesture sent a clear message about how badly I want them to learn. If I accomplished all I hope I did on that first day, year 5 should be simply glorious.