Growing and Growing

5 min

Narrative

This opening Warm-up gives students an opportunity to create a pictorial representation of exponential growth. The purpose of this Warm-up is to help students make sense of the situation coming up in the next activity, in which they are not explicitly asked to make a pictorial representation.

Student Task

<p>Bacteria viewed through a microscope.</p>

Some bacteria are growing in a dish. Every hour, each bacterium splits into 3 bacteria.

  1. This diagram shows a bacterium at hour 0 and then at hour 1. Draw what has happened at hours 2 and 3.

    <p>The picture shows 1 bacterium (an irregular polygon with a double outline and light blue inside) for hour 0, then an arrow to the right, then 3 bacteria for hour 1.</p>

  2. How many bacteria are there at hours 2 and 3?

Sample Response

  1. See sample drawing.

    <p>Illustration of bacteria growth.</p>

  2. 9 bacteria at hour 2 and 27 bacteria at hour 3

Synthesis

Invite a few students to share their drawings and their observations about how the number of bacteria is increasing.

Standards
Building Toward
  • F-BF.1.a·Determine an explicit expression, a recursive process, or steps for calculation from a context.
  • F-BF.1.a·Determine an explicit expression, a recursive process, or steps for calculation from a context.
  • F-BF.1.a·Determine an explicit expression, a recursive process, or steps for calculation from a context.
  • F-BF.1.a·Determine an explicit expression, a recursive process, or steps for calculation from a context.
  • HSF-BF.A.1.a·Determine an explicit expression, a recursive process, or steps for calculation from a context.

15 min

15 min