In this case, that someone is Teachnet contributor, Darcy Hartley-Pinard, from Northview Public Schools in Grand Rapids, Michigan, who offers this activity:

One of our 4th grade objectives is to teach the Excretory System. Unfortunately, there are very few activities to go along with it. This is a hands-on activity that I came up with so that the students can learn both the names and locations of the organs involved in the excretory process, as well as describe their functions. Prior to this lesson we discussed the Excretory System, the organs and their functions. ‹

Objective:
This lesson will identify the structures and order the process of the excretory system through a model or a diagram.

Materials:

• body diagram (use your own, or download our PDF)
• small marshmallows
• glue
• kidney beans
• cafeteria straws
• scissors
• spaghetti (uncooked)
• red yarn
• brown paper sack
• blue yarn
• tag board

Procedure:
I had the students work in small groups. Each group had a brown lunch sack with all of their materials inside. On the outside of the bag I wrote what each student needed to grab out of the bag. I also had the list on the overhead. Students were responsible for getting their own materials out of the bag.

Each student needs:

• 3 Kidney Beans (Represents the Kidneys)
• 3 Spaghetti pieces (Represents the Ureters)
• 2 Marshmallows (Represents the Bladder)
• 2 Straw pieces (Represents the Urethra)
• 2 pieces of Red Yarn (Represents the Arteries)
• 2 pieces of Blue Yarn (Represents the Veins)

One of each item will be used for the key at the top of the tag board. I used rubber cement to attach the body model to the tag board prior to the lesson.

Making the Model:

1. Glue on the kidney beans.
2. The yarn will be approx. 3 inches long. The student will have to separate the yarn into two pieces about 1/2 way up so that the arteries and the veins can go down each leg. Glue on the arteries and the veins.
3. Insert the approximately 1 inch long spaghetti lengths into the mini-marshmallow at an angle. This represents the ureters draining down into the bladder.
4. Insert the approx. 1 centimeter long piece of straw into the bottom of the marshmallow. This represents the urethra. Place glue on the marshmallow only. The spaghetti should be just high enough to‹go over the top of the yarn.
5. The students now have a wonderful model so that they can describe to a partner just exactly what happens in the Excretory System.

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