Mystery Tube

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SWBAT observe how the tube functions in order to create a physical model that replicates the outcome.

Big Idea

Models help us understand science, often changing as we learn more about a topic. The mystery tube helps students develop an understanding of the nature of science by using indirect observations to help explain how the tube might work.

Prepping the Tube for Class

Setting up the tubes will take some time and resources.  They are fairly easy to construct, if you have a hand saw, a drill and are somewhat handy.  Follow these instructions that I created to help you.

This picture shows you the materials needed and how to build the tube:

Mystery tube instructional picture

Source: Understanding Science Lessons, The University of California Museum of Paleontology, Berkeley, and The Regents of the University of California

Most of these materials can be purchased at your local hardware store or other large box stores.

TIP: Ask the school secretary for the TAX ID form so that you don't have to pay tax on your purchase.  You can buy the 2 1/2" PVC pipe in 10 foot lengths and then cut them to your desired length.  You can then purchase caps that will fit over the ends and either buy PVC cement or tape them closed so that students can't open them and you can maintain them over the years.

Instead of the slice of PVC pipe in the middle (as pictured), you can use a large metal washer.


Definitely use nylon rope for its durability.  

This video describes how the tube works.

Overview of Lesson

Overview: This lesson is another good way to introduce my students to the nature of scientific thinking. Providing students with a phenomena to explain helps them develop science and engineering practices that will later be used to build content knowledge and establish connections with crosscutting concepts.  Student groups are asked to determine what the interior construction of a mystery tube looks like, in order to explain how it works.  Because I don't tell them how it actually works, this activity sheds light on the important idea that we don't have all the answers in science.  Additionally, the exercise reinforces the importance of being observant, testing hypotheses, and modeling understanding--setting the stage for future investigations throughout the year.  

Lesson concepts:

  • The process of science involves testing ideas about the natural world with data from the natural world.
  • The process of science involves observation, exploration, discovery, testing, communication, and application.
  • Scientists try to come up with many different natural explanations (i.e., multiple hypotheses) for the patterns they observe.
  • Scientists test their ideas using multiple lines of evidence.
  • Test results sometimes cause scientists to revise their hypotheses.
  • Scientists are creative and curious.
  • Scientists work together and share their ideas.


Reference: Understanding Science Lessons, The University of California Museum of Paleontology, Berkeley, and The Regents of the University of California

Introducing the Challenge

5 minutes

I introduce the activity by telling students that they are going to perform important, vital even, practices in science--hypothesizing about a unknown phenomena, testing possible solutions and creating models that explains what might be happening.  The truth is that all models created by scientists are not perfect or even 100% accurate, and that's what keeps scientists going; we are always seeking evidence that develops our present explanations of the unknown.

I then explain that they will receive the mystery tube and spend several minutes manipulating it by pulling on different strings.  They should record detailed observations, as they will be using them to reconstruct their own model of the tube.  

Student Investigations

25 minutes

I give students ample time to manipulate (play with) the tubes.  As I circulate around the room, I make sure that they are recording observations in their science notebooks.  If students are struggling with recording observations, I help by pointing out occurrences that may go unnoticed and use that as a teaching moment to reiterate the importance of being observant.  

Using Observations to Promote Argumentation

20 minutes

Now that students have collected observations, it is now time for them to hypothesize about what is going on inside of the tube.  I explain that they will be given simple materials and should test their hypotheses by constructing tubes that model what is happening in the actual tube.  

The material bins include many different materials, so that I am not steering my students to one solution.  Also, it is vital to not divulge what is actually happening inside of the tube.  Remember: scientists have never actually seen the inner workings of an atom; we have developed explanations by testing ideas and being observant.  This activity is no different.  Additionally, for every phenomena there is a multitude of different models to help explain what is happening.  Encourage your students to develop different models to explain the same phenomena.  

I like to use the Powerful Questions to Ask Students highlighted by Edutopia:

1.) What do you think?

2.) Why do you think that?

3.) How do you know this?

4.) Can you tell me more?

5.) What questions do you still have?

This will most likely seep into the following class period.  Make sure that you have enough time for students to clean up and store their physical models.  

This video shows some of the models that were used to solve the mystery.  Some of them worked better than others.  I make a point to communicate that science is a process and that finding evidence takes time.  This activity is more about modeling how science works than it is about getting the tube to work perfectly! The video also points out the importance of communicating to your students that everyone has different conceptual and mental models and that is okay!