Showing posts with label ap stats. Show all posts
Showing posts with label ap stats. Show all posts

03 March 2015

Median - The Resistant Little Bugger

One of my most favorite things to discuss in a stats lesson about measures of central tendency is the value or situational advantages of uses mean or median to tell the story YOU want to tell when analyzing data.


While preparing a different post about Google Classroom and Edmodo, I dredged up this old assignment from my Edmodo archives and was smitten by my own work. LOL


Median was described in class as being resistant to change from outliers.  Find a news or blog article online discussing "average" (mean or median) and

1.  Give the url of your article.
2.  Summarize the article - include the variables being discussed
3.  Determine if the article is using median or mean for "average".
4.  Was the article's use of median or mean correct?  Why or why not?

Places to find links with statistics in them:
http://www.freakonomics.com
http://www.census.gov
http://www.espn.com
http://fedstats.sites.usa.gov/
http://www.baseball-reference.com
http://fivethirtyeight.com/

OR - you could Google "average _______", anything really, and get a news article about it.  "Average salary" gave a lot of hits.


To give you more info on the way I graded this assignment, I was looking for some understanding of how students might pick out the difference in use between the two. (Whether or not the article actually said average or middle, using an actual data set to pick that out, searching for clues in the context, i.e. an article discussing how athletes are overpaid would probably use a mean.)

I used this assignment more to generate discussion and thought than as an assessment, but I suppose if you were confident that your students would be successful at this, I don't know why it couldn't be the basis of a performance event or graded writing prompt.

Do you think there are any consistent sources of "stats" articles that I've left off?

01 December 2014

3 Act Math Story - AP Stats - Ferguson Protestors

We're discussing sampling techniques in AP Stats right now, and I think a lot has been discussed in conventional and social media since the August 9th shooting of Michael Brown about the "real" Ferguson.

I teach in the district covering Ferguson, MO, so I've had students in my classes that I'm sure can identify with the popular claim, "I am Mike Brown."

I ran across this article in the NY Post over the weekend criticizing CNN's reporting of the looting, violence, and arson following the grand jury decision on November 24th.


The question that comes to mind first when I see this image paired with this headline is, "Well, how would we know?" There are so many variables playing into reporting of the protests. Who is "from" Ferguson? What is the line between "peaceful" and "violent"? Because St. Louis County is so fragmented with numerous municipalities, is there a big difference between being "from" Ferguson and being "from" one of the numerous small cities/villages/towns that border the Ferguson city limits?

Who's "more" of a part of Ferguson, the demonstrators at night or the people that come to clean up in the morning?

As I included in the teacher notes of this story when I posted on 101qs.com, I don't know if there is an "answer" to this question, but I think its a fantastic opportunity to talk about representative sampling, potential bias, and thinking through demographic and survey data that would be relevant in painting the most "real" picture of the attitudes of Ferguson residents.

The story on 101qs with aligned common core standards and accompanying questions, notes, and resources is here:

Evaluating as a 3-Act Story
  • The image-headline combo is great for getting a reaction or response from students (perhaps too much in my specific case).
  • The question is open-ended and there are several avenues students could take to support or refute the claim made by they New York Post writer.
  • I included several potential resources, including the link to the nypost.com story, census bureau quick facts for Ferguson, MO, a survey report from May 2014 evaluating the effectiveness of government services, and a map of Ferguson breaking down the wards. There are probably a few other data sources kids might need depending what path they go down, but from the teacher perspective of someone else using it in their classroom, I think its quite useful.
  • Since there's not a specific, black-and-white answer, there isn't a lot of closure. I could include a video of Ferguson residents actually peacefully demonstrating, or the dozens and dozens of volunteers that have helped clean up day after day, but that's not as rewarding as "here's the answer. Ta-da!"

In closing I would ask you to rate by the simplest barometer of success for a 3-Act Math story: Is this "perplexing?"

17 April 2014

Are The Chicago Cubs About to Be Historically Bad?

I have a student in one of my AP Stats sections that is a Cubs fan. Its usually a great opportunity to build relationship with him (and the others) by harassing him about how bad they are.

It's in good fun. And educational.

He was telling the class today about the Cubs 4-10 record through the first 14 games of the season. It sounds bad, and it is, but since we know significance tests now, I thought it'd be fun to through their preseason projected win percentage (.413) against their current (.286) to find the chances of a win percentage that low, assuming that the original .413 was close to correct.



Methods
1. Refer to preseason final standings projections from mlb.com to find the Cub's projection along with the other 30 MLB teams.

2. Find the standard deviation of all the team's projections using a spreadsheet.





















3. Use the standard deviation of win percentage, projected win percentage, and current win percentage values to find the z-score and corresponding p-value on the normal curve. Our's calculated to .0015%. That's the likelihood of the Cubs having a win percentage that low, assuming the original projection was correct.

So what's happening here?
We probably shouldn't rule out that the Cubs could be worse than their projected win percentage, but with the team only 9% into the season, its certainly too small a sample size to declare that the team is headed to a historically poor season.





15 March 2014

Blended Learning and Unintended Consequences

A relationship with one of my AP Stats students went sour this week, and it was a little unexpected.

Stats is the class in which I usually have my edtech act "together" because its easier to pilot apps or tools in the smaller classes, they're better at "playing" school so they're more readily willing to try new things, and because they're generally more mature, if things don't go well, we can generally recover, go more "traditional" and still have a worthwhile class period.

Of my preps this year, AP Stats class is the most "blended." Many of those students contact me via email or texting my district monitored Google Voice number. Every project I have them complete is submitted (and completed) electronically. I have a Google Drive folder that they all have viewer access to for notes, handouts, PowerPoint files, worksheets, lesson plans, etc. - there's a lot in there. 100% of these students are signed up for my Remind101 messages. 


So when I had a student complain Friday morning before our quiz that I hadn't "taught [her] the Central Limit Theorem" because she had missed some of class on Tuesday, I was at a loss for words. 

All teachers have to lie (to themselves).

For many reasons, chief among them hope and forgiveness, there are many instances in which teachers have to "lie" to themselves about their students or their classroom in order to walk through the door the next day, teach students, and inspire whatever growth they can conjure from their pupils. It's quite common to give the benefit of a doubt to the student. "She does have a job, 3 other honors classes, and plays basketball - she's got a lot going on." "He has to spend a lot of time looking after younger siblings." "I could have done a better job catching her up after she was absent." "I forgot to get him the homework assignment from yesterday..." 

But. The more we blend our classes, put our materials online, make ourselves (technically) available 24/7, the more we must be real with ourselves. The more the learning opportunities extend beyond your 4 walls and 50 minutes, the more you've got to let it go.

You can lead a student to water, but...
This student was frustrated because she felt like I had not done my job in this particular respect. It's arguable; "if there is no learning, then there is no teaching," might certainly apply to this student's circumstances this week, but when you teach high schoolers, where does your responsibility for effort ever end?

Does it?

The Unintended Consequence:
Because I felt completely resolved in my efforts to share everything with my students, because I had made two content videos last week for note-taking, because I had posted students' class Evernote summaries in our shared Drive folder... I could not rationally wear my teacher-lenses and excuse this student. All I could see was a girl who wasn't taking her responsibility for learning all she could about sample means this week. Using tech in the classroom is supposed to make you feel better, right?


RESOURCES I USED THIS WEEK:
I've asked a lot of rhetorical questions in the post - I hope you made it to the end. Just wanted to share something useful, too.

Evernote - after I noticed a student was doing it on his own with his iPhone, I decided to designate a kid a day take the "official" notes for class in the Evernote app and send them to me so I could post them on a doc in our Drive folder. I'm already in love with this because it saves me 1 or 2 steps in my desire to archive our class sessions for the students. We used the new doc-scanner settings, text, and audio. If I had a premium account I wouldn't have to touch the notes at all because students would be able to upload to a shared Evernote notebook. #gotmethinking

Present.me - One of my videos for the week was made with this #flipclass tool. I like that it makes slides+you easy to create, but there are no YouTube upload options, so it fragments my resources.



Touchcast - The first video I made this week was via the Touchcast app in iOS. This was needed more actual examples worked out, so I needed the whiteboard functionality that present.me does not have. I wrote about my students using touchcast here.


Remind101 - We started a really cool activity from our textbook about the ages of pennies, but didn't get as far as I thought we would be able to, so I had to switch up the plan for the next day. I compiled some numbers they would have had if we'd gotten further, got a share link, and sent it out with instructions for the next day.

Google Voice - Two students texted to my Google number (which shows up in my Gmail inbox) to ask clarifying questions on what I'd sent to them with Remind101.


Google Drive - cre

27 February 2014

Flip Student Project Presentations w/ iOS App Touchcast


I asked a few of my colleagues in the math office about any the reservations they had about having their students make class presentations.
"I think I'm always disappointed with the end product."
"You do it for too long, and they get bored. They don't listen to each other."
"I worry that so many kids are off task and not engaged when the other students are presenting."
When I asked one of them how many days they usually allocate to project completion IN CLASS, her response was, "Days?! How about weeks! If you don't give more time, even those honors kids won't do as well because they're so stressed out about their other classes."

Needless to say, taking out time for project presentations is not something we usually get warm fuzzies about.

THE PROJECT
At the end of every chapter in AP Stats, I usually alternate between summative exams and summative projects. The exams are good because they get more practice preparing for the AP exam, but I think the learning is usually more evident (or lack thereof), and more authentic.

We usually write papers to practice formal, technical writing and integrating math with charts and text, but I was excited about using the Touchcast app recently for my flipped lessons in another class, so I thought I'd have my students kick the tires.

The students had a choice between two projects requiring similar skills, "A Fair Coin," or "Airline Overbooking."

THE PROCESS
The most I usually commit to these projects is one day to allow for questions and clarifications, but there was an obvious need for more support on this project (especially because students under-performed last year), so gave a day for stats work and a day for putting together the slides.

After the slideshow was together, students copied the share link and inserted it as an interactive app in the iOS broadcasting app, Touchcast.

RESULTS
Students were really nervous about being on camera and talking about their slideshows. In a good way, I think. I enjoyed the creative tweaks many of them inserted in their presentation, risks that I think they may have been less likely to take if they were up in front of the room. (even though they knew I would be sharing their videos).

Getting in Touchcast took about a day and a half, but it was time we would have taken any to present, and using Touchcast, everyone was ON TASK because they were making their videos at the same time.



OTHER WAYS TO USE IN YOUR CLASS
  • Students create a current events broadcast for a social studies class
  • Adding in a browser-based whiteboard (like Twiddla) and having students create tutorial videos
  • Students discuss themes of a piece of literature
  • Students create a news broadcast about historical events
  • Demonstrate a procedure for a science experiment
  • Present and critique a work of art or song

13 January 2014

Podcasts in the Classroom for Relevant, Subject-Specific Content


If you only use your smartphone or tablet for playing games, taking pictures, social media, listening to music, or ::gasp:: communicating, you're missing out on great opportunities to immerse yourself in easily-digestible academic content that will probably make you smarter (and more interesting) :)

If you've ever listened to an audiobook, you understand how convenient podcasts can be in "reading" while you perform other tasks, like driving. My wife and I got hooked on Freakonomics one road trip when I checked out the authors' second audio book, Super Freakonomics, from our local library.

The two Freakonomics books, documentary film and the companion blog and podcast is not only about economics. While co-author Steven D Levitt of the University of Chicago IS an accomplished economist, I'd more likely describe Freakonomics as an exploration in the use of data and statistical methodology to study or improve anything.

The consequence of the wide-range of subjects addressed in the Freakonomics podcasts is that you can quite easily find one that piques your particular niche of interest. Here's a list of topics just from the last few months:

Are We Ready to Legalize Marijuana?
What is the Best Exercise?
The Pope's Recent Critique on Capitalism
Are Gay Men Really Rich?
Fighting Poverty with Actual Evidence
For NBA Hopefuls, Zip Code Matters
Who Runs the Internet?

They've also done work on the NFL and sumo-wrestling. :)
But Freakonomics is just the tip of the iceberg! Here's a list of 9 more educational podcasts to share with your students for reflection, introduction, or enrichment

TEDTalks Audio - TED conferences are places to share recent research or discoveries in short, energetic presentations, usually shorter than 20 minutes.
Radiolab - Natural Sciences - Radiolab is a show about curiosity. Where sound illuminates ideas, and the boundaries blur between science, philosophy, and human experience.
CNN Student News
GrammarGirl - Quick and Dirty Tips
Coffee Break Spanish and French
The Math Dude
60 Second Civics
Stuff You Missed in History Class


I'll be using a Freakonomics podcast that I heard over Thanksgiving Break with my AP Stats class to introduce their capstone project for the semester- developing a statistical inference experiment to answer any question they want. I'm hoping by broadening their statistical exposure beyond politics and sports will help them be more creative in their experiment-dreaming.

The students will be assigned the Poverty podcast linked above and given several question prompts to respond to - about half of which are about the actual content of the podcast and half more about reflecting on possible topics for the capstone project in May.

Here's a link to the assignment.
"The Relevance of Statistical Work"


03 January 2014

The Daily 5 in Grades 6-12: Boxplots Partner Reading

This post is the 2nd in a series devoted to adapting the literacy tenets of "The Daily 5" to a secondary classroom with 50 minute periods. You can catch the whole series here.

Daily 5 Tenet #3 - READ TO SOMEONE

Sit some seniors down in a classroom and tell them they're going to read to each other. They'll look at you almost as skeptically as I did this summer when a colleague had us do it at a reading training over the summer.

"Really," they think. "Do we have to," they ask. "Yep," You will answer.

I modeled it with a different random book I pulled out of the reading corner in my room, and I think that took some of the hesitancy out of it. Granted, my AP Stats students are usually up for anything, but I had full participation in this partner read today with no groaning and pleading.

Here was the text from our textbook, The Practice of Statistics, 2nd Ed.

Not the most engaging passage ever, but certainly not bad by textbook standards, and definitely high on ease of implementation.



How Do I Do This?
A partner read is as simple as it sounds. Two students take turns reading paragraphs to each other. Depending on the individual students' reading levels, partner read could be an opportunity to practice:
  • vocabulary building
  • reading fluently
  • listening to fluent reading
  • auditory comprehension
  • monitoring for understanding
You may be wondering, "Why not just have students read to themselves silently? I'd rather have that than a dozen kids all reading aloud at once."

I don't think I'm alone on this, and I know I've seen students do it - how often do you skip over information that ended up being important when you are reading to yourself? Yes, skimming is a great technique for speed reading, and is wonderful for getting the gist of an entire article, but I've seen my students routinely discover a few key words they missed reading to themselves after I make them read back to me aloud.


To The Next Level
Reading is always better with writing! Since your students will already be in partners, to wrap up the activity, I had them agree upon 2 summary statements for the passage. Here are a few samples.



I felt like these turned out more as facts-from-the-text than they were summary statements, but once they were shared in class, we got a clearer picture from their parts together.

21 November 2013

Because Weighted Averages - Fighting Back the Points Hounds


Although we're continuing the conversation and including more teachers in standards-based grading training in my district, most all of the classes remain traditionally graded with categories for homework, formative assessments, summative assessments, and finals that were agreed upon by each high school.

It seems like most every class I grade on our traditional grading scale, I'll have kids who start to get homework bugs by November. "I'm doing all of my homework - how come I'm still failing?" is what they'll ask me. No matter the number of times I tell them that those 2 missing homework assignments are not the reason they don't have the grade they want, they insist that "every little bit will still help." While that is technically a true statement, it misses the point. Although we've devalued homework to 10% of our averages to stress assessments and projects in grade calculation (to stress evidence of learning), as long as we have a category that includes homework, the point hounds will be scrounging at the table for their point scraps.

Here's what I conclude:
As long as I include homework in the calculation of grades, I will always fight the students and parents that want to squeak out every homework point "just in case."

It takes persistence and perseverance through the first several weeks as students adjust, but I always feel most successful evaluating my students' learning the more I stress mastery, and I devalue points through standards-based grading.

In the meantime, I created this video to as a resource to my students who want to set goals and track their weighted averages.



07 October 2013

Writing in Math: Modeling is Powerful


My students encounter writing most in my AP Statistics class. Because of the responsibility to my students to prepare them for an AP exam that will require them to justify the statistical tests they conduct, the conclusions they make, and the observations they draw from graphs, data sets, or computer outputs, I have no choice but to engage them in writing tasks.

Students will not learn to write technically on their own. It's unnatural. It's "hard."
For the majority of my students, AP Statistics is their first exposure to sustained, technical, and descriptive writing. For the most part they've had short answer responses on some quizzes in other courses that will require them to explain "why" they think they're answer is reasonable, or how they came to their answer, but I find myself stretching and pulling all of 1st quarter to get these kids to write more than a sentence per prompt question. 

Consider the following histogram of a roughly symmetric, normal-ish distribution (if I'm losing you there, just know that this bar graph should be symmetric with a high peak in the center and long tails to both positive and negative infinity):

A pretty common prompt in the section where normal curves are introduced would ask something like, "Describe the shape of the distribution." Students usually feel pretty good about themselves if they remember to point out that its symmetric, and has a single peak. If they're getting frisky, they'll mention the tails off to the left and right, and point out the because the distribution is not skewed (with the data clumped in the right or left with a long tail to either side), that we know the mean and median would be roughly value, in the middle of that peak. 

I've come to expect these habits early in the year, so I lean heavy on giving positive feedback for effort (they wrote something), and always give a more specific example of how I would have refined what they said, or I read from my solution manual (sometimes even correcting the manual if I think the manual could have been more specific).

Students cannot know good technical writing without reading technical writing. 
Ironically, I think your textbook is a good place to start, because every section has passages you can easily pull that attempt to succinctly explain vocabulary or walk students through a procedure.

You hope there comes a time in every student's educational career where they stop filling their writing with flowery words that don't mean anything; that they would get to the point, especially in technical writing. However, the pendulum soon swings the other way and students write much less than they should, forcing the reader to assume much of the knowledge the student should be demonstrating.

To refer to the histogram again, I think a student given a prompt of, "Describe the histogram," or "Describe the characteristics of this data set" that had not been introduced to statistical terminology would probably write too much, and still not relay the point about symmetry and the placement of the mean/median. "There are 12 bars on the graph. The first one starts and -3 and goes up a little bit past 0.0..."

I've written all of this so I could share how embarrassingly inspired I was reading this report of a recent Pew Research Survey on the Affordable Care Act, and the role of Republicans vs. the President in the shutdown.

The writer of the report spent several paragraphs describing their methods, the lengths the survey designers took to eliminate response bias from the participants, and examining the bias they were unable to eliminate through their methods. It's just a lot of good, descriptive, writing that will be great for the Experiment Design chapter in the AP Stats curriculum. 
"The analysis in this report is based on telephone interviews conducted October 3-6, 2013, among a national sample of 1,000 adults 18 years of age or older living in the continental United States (500 respondents were interviewed on a landline telephone, and 500 were interviewed on a cell phone, including 250 who had no landline telephone). The survey was conducted by interviewers at Princeton Data Source under the direction of Princeton Survey Research Associates International. A combination of landline and cell phone random digit dial samples were used; both samples were provided by Survey Sampling International. Interviews were conducted in English. Respondents in the landline sample were selected by randomly asking for the youngest adult male or female who is now at home. Interviews in the cell sample were conducted with the person who answered the phone, if that person was an adult 18 years of age or older. For detailed information about our survey methodology, see: http://people-press.org/methodology/. 
The combined landline and cell phone sample are weighted using an iterative technique that matches gender, age, education, race, Hispanic origin and region to parameters from the 2011 Census Bureau’s American Community Survey and population density to parameters from the Decennial Census. The sample also is weighted to match current patterns of telephone status, based on extrapolations from the 2012 National Health Interview Survey. The weighting procedure also accounts for the fact that respondents with both landline and cell phones have a greater probability of being included in the combined sample and adjusts for household size among respondents with a landline phone. Sampling errors and statistical tests of significance take into account the effect of weighting. The following table shows the unweighted sample sizes and the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the survey: 
 
Sample sizes and sampling errors for other subgroups are available upon request.
In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.
"

27 August 2013

Emergency Lesson Plans: AP Statistics

Someone came to the blog via this search a few days ago and found this post about my son's hospitalization as catalyst for my decision to finally MAKE emergency sub plans, but I'm sure they left disappointed, because I didn't actually share my plans in that post. :)



Principles for Emergency Planning
In the previous post about emergency sub plans, I laid out these principles I was going to follow as I crafted my plans:
  1. When choosing learning objectives, I'm going to focus on things we are currently addressing in our PLC Smart Goal, or critical skills that consistently need reinforcing. 
  2. Have a back up to the emergency plans in case students finish quickly
  3. Crowdsource your emergency plans with co-teachers.
  4. To give yourself ultimate flexibility (particularly in your emergency back-up), keep a class set or at least enough for 2 kids to share of your course textbook in a closet or cabinet nearby.
  5. Make it something you'll at least consider grading when you return.
Emergency Planning for AP Statistics
I have three thematic goals for my AP Stats students throughout the year: data gathering, data crunching, and technical writing, so all of the options listed here, so if I stick to those goals (principle #1), I'll have something that can be mostly applicable for students no matter where we are in the curriculum.
  • AP Practice Exam: The College Board releases items from old exams on their website. Might as well take advantage.
    • 1997 Released Practice Having students complete this all in one hour would be an impossibility, so you've got at LEAST two days of material here. I would have students work in pairs on either the multiple choice or free response and collaborate quietly.
    • Free AP Stats Practice Exam This test is secured behind your College Board Course Audit login, so be sure to have that info handy.
  • Data Collection/Experiments
    • "How Long Is a Minute" Materials and resources are usually intentionally scarce on guest teacher days, so its impractical to have plans that require elaborate handouts or materials list. This experiment is my current emergency plan, and I love it because its easily approachable early in the year before we've done a TON of stats work, and only requires a clock in the classroom with seconds.
    • Probability Simulator TI 83/84 app + this handout The handout is actually for a more extensive project, so you'd have your students BEGIN the project on this day (and work on it periodically over a matter of days), or just have students complete a portion of the work.
  • Probability Based Gaming