Mystery Box

Author(s): SEP Coordinators

Lesson Overview

Grade level(s):

Middle School (6-8), High School (9-12), Grade 6, Grade 7, Grade 8, Grade 9, Grade 10, Grade 11, Grade 12


Science Skills


Science skills: An approach to critical thinking

Big ideas(s):

How do scientists approach the investigation of things that cannot be seen or touched? What roles do models play in science?

Vocabulary words:

Mystery Box, Scientific Method, inside, outside, visible, invisible, prediction, hypothesis, model,  experimental model, reproducibility,evidence,results,observation

What you need:

Mystery Box with a large funnel, plastic tubing, two smaller funnels and a flask or container, smaller plastic tubing, cotton balls, food coloring. See attached photos.

One beaker to collect liquid

One jar with water


Students should work in pairs at first. Then bring pairs together to refine the model drawing. Finally, have a whole group confefence where each group presents their findings.  If students are constructing models, groups of four will work well.


Teacher brings the Mystery Box to the classroom and shows the box to the students. The only visible thing in the box is the funnel at the top and at the bottom there is a container to collect whatever flows from the box. The teacher then pours water in the funnel on top and colored water flows at the bottom. A turn to the upper funnel and pouring more water will either produce a diferent colored water or no water at all. The top funnel can be turned to three positions that produce different results. The challenge question is: What does the box look inside in order to produce the observed results? You can decide whether to tell the students that you need to rotate the funnel to get the different results.

Time needed:

If the students are simply drawing models of the Box, the session will take one class period. If models are to be constructed, then another class period will be needed

Author Name(s): 
SEP Coordinators

This lesson is designed to help students better understand the nature of science. It uses a Mystery Box (see attached photos) which has a funnel at the top and a beaker underneath. When water is poured into the top funnel, colored water flows out the bottom. A turn of the funnel and then pouring in more water results in either a different colored water or no water at all. The teacher demonstrates this Mystery Box to students and challenges them to propose models of the inside of the box. The students draw models of what they think the inside of the box looks like and share and discuss these models. Students can also construct their own mystery box using cardboard boxes and other common materials. For this option, you will need an additional class period.

Learning goals/objectives for students: 

Students will better understand why scientists use models to help them explain things that cannot be seen or touched.

Students will experience proposing a model based on indirect evidence.

Students will experience making a prediction based on observations and collected evidence.

Content background for instructor: 

Students may be frustrated by not being able to see the inside of the box. This frustration can be eased by having students construct models and then they can see if their results are similar to those of the Mystery Box.

You can also let students know that although everyone’s drawing and/or constructed models may be different, they can each be correct if they fit the observations.

Getting ready: 

Be sure all materials inside the box are there and connected properly. Add a different color of food coloring to each of the cotton balls. Put the cotton balls on each of the smaller funnels.

Lesson Implementation / Outline


Scientific discoveries are made because humans are driven to understand how things work. But many of the things we want to uderstand are either too small to be seen (atoms, organelles, cells) or too large and distant (planets, stars). Careful observations and investigations lead to the development of models that are then tested to see if they produce reproducible results and observations. Models and ideas are continuously revised and reworked to better fit observations and results.


Mystery Box demonstration. Put the box on top of a table and show the students the box by rotating it around and showing the top funnel. Do not show the inside of the box. Put a container/beaker at the bottom and ask the students what they think will happen when you pour water in the top of the box. Collect several diffferent answers. Pour the water in with the result being colored water flowing into the beaker. At this point, you can have students make an initial drawing of what they think the inside of the box looks like and/or you can ask them to talk with their partner about what they think is going on. While they are doing this, you can turn the funnel. When ready, pour in more water and water of a different color will come out. Now have students revise their ideas. Finally, turn the funnel again to the third position; here, when you pour more water in, none comes out. Again, have students revise their ideas.

Ask the student pairs to draw a model of what they think the inside of the box looks like.  Walk around as students prepare their models and make groupings of several pairs depending how many large presentations you may want to have.

Groups of pairs then present their models to each other and discuss them further in order to develop one model for their group. Have students draw this model on large poster paper.

The whole group conference takes place and the models are presented. Encourage your students to ask questions about the models.

An extension of the lesson is to have the students build their models using cardboard boxes and other common materials and then test them. Students may need to revise their models. You can emphasize that scientists need to continuously revise and rework their models and ideas about how things work as they make more observations. Additionally, you can let students know that although everyone’s drawing/model may be different, they can each be correct if they fit the observations.

Checking for student understanding: 

Students' understandings will be observed by how they are able to make progress in their discussons, drawings,  and models. In this activity there is no right answer and the inside of the box is not shown at all.

Wrap-up / Closure: 

The closure will be the whole group conference presentations. Students will share their ideas about what they think the inside of the box looks like and you can assess how well developed/accurate their models are.

You can also ask students to write about or discuss what they have learned about science and how science works from this lesson. This process and the group interaction (group work and conference to present findings) mimic what scientitsts do at meetings and conferences. And, the advancement of knowledge is due to refined models and the reproducibility of results. Only when something is reproducible over and over and over does it becomes accepted as a working model.

Extensions and Reflections

Extensions and connections: 

You can use this activity before teaching about how scientists have come up with models of the atom.


Have the students reflect on what they learned about science from this lesson.

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NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Crosscutting Concepts: