Expanding the Use of Exponents Part II

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SWBAT apply the rules of exponents to a real-world situation.

Big Idea

To consolidate understanding of the rules of exponents, students apply their skills to a scientific scenario involving bacterial growth.

Warm Up

5 minutes

To provide an additional preview for today's performance task, I give students an exponent string table to simplify for Warm Up.pdf.  This will give them the opportunity to practice simplifying both positive and negative exponents and with recognizing the pattern that emerges. This practice will hopefully clarify any misconceptions students may have about negative exponents.

Work Time

35 minutes

Because I previewed this activity for students the previous day, I am confident they have the information needed to get started with little or no support from me.  Students are seated in homogeneous table groups of 4 that are assigned after each formal assessment so that there is a balance of skills levels at each table.

As I pass out the task, I encourage students to use their resources and follow our "SEE3B4ME" (see three before me) rule.  If they exhaust the help of peers at their table, they may ask for clarification from me.  This classroom expectation was established early in the school year and helped establish the climate that there are many math experts in the room from whom we can seek help or support.

Once students have their papers, I set the class timer and they begin to work.

As students collaborate on the assignment, I circulate the room, eavesdropping on conversations, both task-related and off-task. When I hear off-task topics, I remind students I should be hearing "math talk", another classroom expectation established early in the year.

I make note on my clipboard of particularly interesting comments, like an argument between two tablemates, where one is trying to convince the other that when completing the table with the time before the experiment begins, they should be writing numbers less than one, not 500.  I will bring this idea up during closing to reinforce the thought process needed to decide how to apply scale when representing data.

I continue to gather examples of essential points for the remainder of the work period. Several groups need assistance simplifying the two rules provided.  I support them by guiding them through how to solve when t=2.  This example is the small push they need to set them in right direction.


5 minutes

Once the timer sounds,  I bring the group's attention to the smartboard for closure. I bring up a slide of the day's Work Time assignment and begin to call on specific groups to share their thinking for each section of the assignment, using my clipboard for reference.  For example, I said, "While you were completing the table, I heard Angel explain something important to Guillermo. Can you tell the class what you said to him?"  I continue in this way with each question, drawing in student explanation when I have examples noted on my clipboard. By doing this, I am helping all students benefit from the student conversations held at each table. My hope is that this strengthens everyone's understanding of the problem.

As class ends, I ask students to scale their understanding of today's work by using our classroom learning scale of 1-5 (1-I don't understand at all; 2- I understand a little; 3- I'm starting to understand; 4- I understand well; 5- I could teach someone else this concept).  The responses range from 3 to 5, which tells me I will need to continue to reinforce the concepts that were included in this task.