• Students will be able to describe the function of the kidney.
• Students will design a filtration system and identify the ways in which it is similar to the kidney.
• Students will discuss the different issues that may arise in the kidney.
• Students will form a conclusion that describes why kidneys are important to the body.

This lesson encourages students to use the engineering design process to create a filter that resembles kidney filtration. They will learn about the issues that arise in the kidney through a jigsaw activity and will use the evidence they gather to respond to the claim that the kidney is an essential organ in the human body.

Teacher Preparation

Before class, prepare the dirty blood samples. This activity is best done in pairs, so you will need one dirty blood sample per pair. Lay out all the filter building materials in a common space for students to grab as needed.

Tip: This activity can be easily accomplished with a coffee filter. Avoid providing actual filter paper for this activity to create a challenge for your students.

Students will need crayons or colored pencils for this activity. Print out one set of the Jigsaw Activity reading pages for each group of four students.

Lesson

Using the Get to Know Your Kidneys Slide Show, ask students to write down how they think urine is made. A few prompt questions have been provided on slide 3. Allow time for students to think independently. Then, have them to share their thoughts with a partner.

Give students 1 minute to list all of the waste products their body makes. Ask students to compare their list with a partner.

Discuss the three body systems that remove waste from the body. Have students match their waste products to the appropriate system.

Prompt students to try to label the excretory system in their Get to Know Your Kidneys Lab Notebook. Show students the labeled diagram and give them time to check their labels. Have students label and color the parts of the excretory system in their lab notebook. When finished, ask students to point to their kidneys. They should point to their back, just below the ribcage.

Explain how the kidney is actually made of smaller units called nephrons. The nephrons do the actual work of the kidney. Provide students with time to label and color the nephron picture in their lab notebook.

STEM Activity: Learning About Kidneys Video
Play the video. When finished, use the graphic to educate students on the engineering design process. It is important to emphasize that they will be asked to create something that solves a particular problem. They may not get a chance to improve and redesign their filtration system. Although, if time permits, this would be a great challenge!

Tip: If class time does not allow for you to do the engineering challenge in the same class period, students can draw out a plan so that they are prepared for the next class period.

Kidney Filter Engineering Challenge (30 minutes)
Arrange students into pairs and distribute one dirty blood sample to each pair. Provide time for students to discuss and plan before they go to get materials. Allow about 15 minutes for students to create a filter system and filter their blood. The goal is to remove as much waste as possible from the sample, while preserving water and red blood cells. Ask students to label their cup and place it on a front table.

Discussion
The nephrons work by filtering waste, nutrients and water out of the blood while keeping blood cells in the blood vessels. Then, the nephrons allow nutrients and water to be reabsorbed into the blood in order to stay hydrated.

Notice which blood samples have low water. Some students may have used cotton balls, which absorbed all their water. This is a good opportunity to describe why hydration is important. Ask students to think about what they would feel like if their blood had a low water level (sluggish, tired or dizzy). Ask students what they think they should do if they feel this way. Answer: Drink more water!

Provide student class time to reflect on their model. How is it the same and different than the nephron? Wrap up by having students clean up the lab space.

Kidney Disease Jigsaw (25 minutes)
Have the Jigsaw Activity Printables ready. Split students into groups of four. Each student in the group will get one of the four reading pages, lettered A through D.

1. Before beginning, make sure students understand the flow of the jigsaw activity. Remind them that they will be responsible for teaching their group members the information provided on their card.
2. Give students 5 minutes to review their reading page silently and write answers to their questions.
3. Move students into expert groups. These are the students who share the same letter reading page. Allow students 5 minutes to discuss the questions and answers with their group.
4. Move students back to their original group. Allow 8 minutes total for students to teach each other about their information. This means each student has 2 minutes to discuss their reading page. Create a rule for who should talk first, such as the student who has the next birthday.
5. As a class, go over some of the main takeaways from the reading pages.

Conclusion
At Sanford Research, researchers are examining two types of cells that line the collecting duct of the kidney. Principal cells reabsorb water. Intercalated cells help to balance the pH, which is the measure of how acidic or basic a water-based solution, like blood, is.

Researchers are trying to figure out how the body determines which cell types are created. More specifically, they are looking at why principal cells can change into intercalated cells in some people.

To wrap up this lesson, ask students to respond to the claim that the kidney has an essential function in the body. They should provide evidence from their lesson to back up the claim.

Sanford Connection
Kamesh Surendran, PhD, and Indra Chandrasekar, PhD, study multiple cellular mechanisms involved in kidney function. Their work helps to shed light on the complexities of the kidney in order to develop tools to address kidney disease and cellular changes. Learn more about the research being done by Dr. Surendran and Dr. Chandrasekar.

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