Sampling Simplified

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SWBAT understand and apply randomization methods to sample studies.

Big Idea

Simple-Stratified-Systematic-Cluster-Convenience...What the heck do all these terms have to do with mathematics?!

Set the Stage

7 minutes

Put it into Action

45 minutes

Teamwork 30 min: You will need copies of the Random Sampling Methods handout for this activity.  After we've finished discussing some of the sampling methods available, I tell my students that today's activity will allow them to make their own decisions about how to collect information about a given population.  I tell them they'll be working with a partner (see my strategies folder for assigning partners) to choose a method and collect data about three different populations in our school. I also advise them that they will be presenting their work to the class at the end of the activity and will need to be prepared to justify their choices.  I give each student a copy of the Random Sampling Methods handout and ask them to read through it with their partner.  I give them time to complete that task, ask if there are any questions and answer those.  Generally at least one student will ask about using the computer to find student ages or textbook information and I tell them that unfortunately, those files are not available to them or to me.  I ask my students to check in/out with me if they need to leave the classroom and remind them to use their time wisely, then let them get to work.  As they begin discussing their options I walk around observing and offering support and occasional redirection as necessary.  My school is small enough and the students I have in this class are mature enough to move around collecting data without problems, but if that isn't the case for your classes, you can generate populations within your classroom.  For example, you can have them sample the words in their textbook, the thumbtacks in the walls, the tiles on the floor, or the spitwads on the ceiling.  I give my students reminders about the time when they have ten minutes remaining and when they have two minutes remaining, to help them in organizing their presentations.

Student Presentations
15 min: At the end of 30 minutes, I ask for teams to volunteer to share their results with the class.  Each team explains what sampling method they chose and why for each population and then shares a summary of their data, which we post on the front board.  The non-presenting students then question/critique the presenting team's choice of sampling method and also their data summary.  Since each student knows that his/her team will be critiqued they are generally courteous in their discussions and I like to give my students lots of opportunities to give and get feedback from their peers.  (MP3)

Wrap it Up

3 minutes

After all the teams have presented, I ask the students to record the data summaries on the front board.  I tell them that I want them to write a brief evaluation of these summaries in light of how the data for each was collected for class tomorrow.