# Lesson 15

Using Water Efficiently

### Lesson Narrative

In this lesson, students use their understanding of proportional relationships to explore whether baths or showers use more water. The warm-up gives students a chance to think about what they would need to know in order to answer this open-ended question and to share their ideas with classmates. In the main activity, students seek out resources to help them answer the question and they create a display to report their findings.

If possible, allow students the chance to work on their own to find values to aid in their solutions. For example, sizes of typical bath tubs are usually listed on websites for hardware stores that carry baths for installation. If these resources are unavailable, some typical ranges are provided or reasonable estimates can be used.

### Learning Goals

Teacher Facing

• Apply reasoning developed in this unit to determine whether a proportional relationship models a situation about water usage.
• Make simplifying assumptions and determine what information is needed to solve a problem about water usage.
• Use proportional relationships to analyze (orally and in writing) a problem about water usage.

### Student Facing

Let’s investigate saving water.

### Required Preparation

Internet enabled devices are only needed if students will conduct their own research. Tools for creating a visual display are only needed if students are making posters of their methods and results in the second activity.

### Student Facing

• I can answer a question by representing a situation using proportional relationships.