Fishy Mixture Water Quality Inquiry Lab (Part 3/4)

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SWBAT identify, classify and separate different types of mixtures based on physical and chemical properties of matter.

Big Idea

Students explore how complicated mixtures are all around us, affecting us in ways we rarely think about. While some mixtures help us, they may harm the environment.


The Fishy Mixture Water Quality Inquiry Lab is an inquiry project including multiple lessons taught over the span of 1 to 2 weeks. To help manage the magnitude of this project, you will find the project split into 4 parts.

  • Part 1 includes the ENGAGE and EXPLORE components of the lesson; Time: 2 - 3 50-minute lessons or equivalent block periods. 
  • Part 2 includes the EXPLAIN component of the lesson; Time: 1 50-minute lesson.
  • Part 3 includes the EXTEND component of the lesson; Time: 2 -3 50-minute lessons or equivalent block periods.
  • Part 4 includes the EVALUATE component of the lesson; Time 2 50-minute lessons or equivalent block period.

Next Generation Science Standards

This lesson utilizes many of the Next Generation Science Standards. I've described how these standards are met in this video.

In addition, details of the alignments of content standard to concepts and practices are found in the resource Fishy Mixture NGSS Alignment.


100 minutes

The purpose for the EXTEND stage is to allow students to apply new knowledge to a novel situation. This step of the lesson is where students plan, design, build and test their mini waste water treatment plants (WWTP). 

1) We review the purpose of this lab: To separate a mixture based on the properties of the mixture.  As a group, we establish the "rules" using the Fishy Mixture Water Quality Rubric.  I have students consider the following factors during the design process:

   - Materials Use (Fewer is better.)

   - Water Quality (Clear is better.)

   - Water Quantity (More is better.)

   - Materials Recovery (Students can recycle useful materials like the ball bearings or clean cups.)

I advise students that the rubric will be used to score their two samples. They will be able to use the better of their two scores. I remind them that the score will not be part of their grade, but rather, a way to quantify their success at separating the mixture.

2) Students are now ready to complete the Fishy Mixture Lab Sheet collaboratively with their groups.  I require students to complete all planning and have a consultation with me where they present their ideas prior to building or testing. I do let them "window shop" at the supplies table, so that they might see what is available. For an example of student planning: Fishy Mixture Student Work - Planning. This video explains how to combine science and engineering when designing lessons like this one:

For additional discussion about the design process, read this section's reflection: Plan, Build, Engage.

3) Students build their WWTPs. To manage supplies, I give each table an index card. They are required to present a detailed materials list to me in order to keep track of the supplies they use.  At the end, I will take any clean, unused or recyclable materials back. I mark these on the index card, so they can use the rubric to calculate their scores.

4) Students use their WWTPs to separate two samples. They are allowed to modify their design as long as they keep notes on the changes. During the process, they are to make observations and record them on the lab sheet.

5) SAFETY: I require all students to wear goggles and abide by safety guidelines because there is glassware, heat and unknown chemicals out in the lab.

Continue on to Fishy Mixture Water Quality Inquiry Lab Part 4.