Vocabulary: organ, kidney, nephrons, waste, blood, vitamins, minerals, urinary system, bladder, ureters, scientific method, hypothesis, data, observations, procedure, results, conclusions, mass, circumference

Materials: eggs, salt, sugar, water, vegetable oil, clear cups, permanent markers, graduated cylinders, measuring tape, spoons, balance, sponges, paper towels, student worksheet

Lesson: 

• Introduction- What are the essential things that humans need in order to survive?  [make list on board: air, water, food, shelter]. Of the ones that are on the board, which one(s) have to do with what is going on within our body? [air, water, food]. So what happens to those 3 items once they go into our bodies? [Eventually something comes out like CO2 or waste/urine. We have specific organs in our body that are like little machines that have very specific jobs. One of the most important organs is one that people often overlook: our kidneys. Show a diagram of the kidneys and how they are a part of the urinary system.] Looking at the diagram, why do you think our urinary system, including our kidneys are so important? à they help to remove waste in the blood. What kind of waste? Well, think about what kinds of foods we eat – how do they taste? [sweet, salty, greasy, spicy].

• Question- Now that you know a little bit about our kidneys, let’s try to use our knowledge of the scientific method to figure out a question: What kinds of waste do our kidneys interact with?

• How are we going to solve this problem? Each group will get 4 “kidneys”, which are raw eggs. Each group will also need 4 clear cups, 1 permanent marker, 1 spoon, 1 marked cup with granulated sugar with a spoon, 1 marked cup with table salt with a spoon, 1 marked cup with vegetable oil with spoon, and a pitcher of water. Ask students how we can use these materials to figure out if it is sugar or salt that is being removed from our blood by our kidneys.

• Set up: Once a procedure is established and written on the board, have groups begin setting up their experiment. Be sure to test before hand to make sure that students add enough sugar/salt to the point of saturation in the water.
  • 4 cups labeled: water, salt, sugar, vegetable oil
  • Measure determined amount of water from pitcher in graduated cylinder and pour carefully into the 3 cups so that all cups have the identical amount. Be sure that the amount of water determined leaves enough room to add sugar/salt and to stir.
  • Add the determined amount of salt into the salt cup with water and stir until completely dissolved. Add the determined amount of sugar into the sugar cup with water and stir until completely dissolved.
  • Label each egg with a 1, 2, 3 or 4. Measure the eggs’ mass and circumference around the middle. Record.
  • Place each egg into the designated cup. Record observations.
  • Let it sit over night.
  • Predict or hypothesize what you think will happen and write it down.

   

• Clean up and wrap up with students for the day’s activity. Share hypotheses and reasoning.

• Results: When students return the following day, have students review the urinary tract and revisit their hypothesis. In their groups, first observe their cups and record any changes that the see. After recording, hand out paper towels, balances, and measuring tapes. Gently wipe off each egg at a time, make any kind of observations, then measure the mass and circumference of each one. Record.

• Analyze the data: Finish the data table. Show students how to fill out the graph using their data table, colored pencils, and ruler. Once students’ graphs are completed, have their groups come up with a sentence for each sample as to what happened, and a sentence or two describing if and how their experiment could lead to any kind of conclusion about the question posed.

• Demonstrate: take one group’s egg in water sample. Cover the egg in vinegar to dissolve the shell. Remove and then carefully pierce the membrane with a needle à jet of water will shoot out. Ask students why this happened. Does this help to explain some of the results in your table?

• Review and Explanations: go over what students observed as a class. Explain that the changes in the egg that they observed and recorded show that those substances are ones that can affect our own kidneys. If the kidneys did not remove them, these wastes would build up in the blood and damage the body. The actual removal of wastes occurs in tiny units inside the kidneys called nephrons. Each kidney has about a million nephrons. Most kidney diseases attack the nephrons, causing them to lose their filtering capacity.

New York State Standards: 

Standard 1:  - Analysis, Inquiry, and Design

         M3.1 Critical thinking skills are used in the solution of mathematical problems. Use appropriate scientific tools, such as metric rulers, balance, graph paper, graduated

         cylinder to solve problems about the natural world.

         T1.3 Generate ideas for possible solutions, individually and through group activity; apply age-appropriate mathematics and science skills; evaluate the ideas and

         determine the best solution; and explain reasons for the choices.

Standard 6: - Equilibirum and Stability – Models are simplified representations of objects, structures, or systems used in analysis, explanation, interpretation, or design

Standard 7: - Connections – The knowledge and skills of mathematics, science, and technology are used together to make informed decisions and solve problems, especially those relating

         to issues of science/technology/society, consumer decision making, design, and inquiry into phenomena.

• analyze science/technology/society problems and issues that affect their home, school, or community, and carry out a remedial course of action