Not everything can be seen or observed directly. As scientists, what should we do when we still want to learn about these phenomena? This lesson can be used as an introduction to scientific models (the related science practice is developing models to describe unobservable mechanisms - SP2) or works as a lead-in lesson to Let's Get Atomic - Investigating Historical Models or Cooking Up Atoms Investigation. In addition to practice using and evaluating models, students consider limitations of data analysis and seek to improve precision and accuracy of data with better technological tools and methods (SP4). Another lesson related to the practice of collecting data is Collecting Data: Observation and Inference, which could be used in conjunction with this lesson as well. The Crosscutting Concept that pulls all of these lessons together is this: Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts; therefore, complex natural and designed structures/systems can be analyzed to determine how they function (CCC).
This lesson is really a Science Practice and Crosscutting Concept lesson but is better used in context as a precursor lesson to help students access the Matter and Its Interactions Core Disciplinary Idea: students model simple molecules and extended structures (MS-PS1-1). A basic understanding of atomic structure is fundamental to further study of molecules, chemical reactions and properties of matter. By exploring models and limitations of models, students are well-equipped to further their inquiry into atomic models.
In order to ENGAGE students in this lesson, students respond to the prompt:
What are some things in nature that we can't directly observe, but we still know (or want to know) about?
Students are able to generate a list based on their interests, curiosities and background knowledge. An example list of possible phenomena can be seen here: Black Box Problems Teacher Notes or here: Black Box Problems and Atomic Theory Presentation. At this point, students are introduced to the concept of "Black Box Problems":
A black box problem is a phenomenon that is difficult to study because we don’t have the technology to observe it directly.
Once students have gotten their interest piqued, they view this image:
With a partner, students make two conclusions about the graph. This graph is a great way to visualize the small sliver of the known universe that we, as humans, can observe through sight and sound. Students are surprised to see just how little humans can directly observe, which leads the class into a discussion driven by this prompt:
So, if we can't see it or observe it directly, how do we learn about...(insert topic from class generated list: dinosaurs, black holes, deep sea vents, etc.)?
At this point, the real crux of this lesson is introduced: scientists use tools, technology and models to collect data about unobservable phenomena. To give students a hands-on experience with this concept, students experiment complete a Predict - Observe - Explain protocol (Predict - Observe - Explain: A Protocol for Demonstrations) with a mystery tube (Mystery Tube Lesson Plan):
Students predict what they think will happen when the various strings are pulled, make observations about the string movements and develop an explanation of what they think is happening inside the tube. Depending on the time available, students can make their own prototypes to test their hypotheses. No matter what, when students ask, "So what's inside the mystery tube?". The only answer can be, "I don't know! It's a black box problem. If we can't observe it, we'll have to find out in another way!".
The EXPLORE stage of the lesson is to get students involved in the topic so that they start to build their own understanding. To help students explore, students follow the procedure in the Black Box Problems Investigation. This investigation uses puzzles such as these Black Box Puzzle 1 and Black Box Puzzle 2 (available as a kit from Flinn Scientific).
Teacher Note: If the budget is tight, you can make your own Black Box Puzzles out of check boxes (or any small box that has a removable lid), marbles and foam core board. Each of your puzzles should have a different pattern inside and should be kept secret from your students.
Students complete the Background Information section of the investigation using what they learned during the class discussion in the ENGAGE stage of the lesson. For notes to review this section with students, use: Black Box Problems Teacher Notes or Black Box Problems and Atomic Theory Presentation
To investigate Black Box Problems, students:
- Find a puzzle. Write the number of the puzzle in the appropriate data table.
- Carefully shake and tilt the puzzle.
- Observe the sound and feel of the steel ball to try to determine the pattern in the puzzle (make a hypothesis).
- Record your hypothesis in the appropriate data table by drawing a model of what you think the puzzle looks like,
- Test your hypothesis by moving the ball carefully along the walls in the puzzle. If you modify your hypothesis, record your new hypothesis model in the appropriate data table.
- Repeat steps 1 – 5 with at least three other puzzles.
Teacher Note: Remind students that they DO NOT OPEN THE PUZZLES! Students are so tempted by finding the "right" answer, that they will often open the puzzles. Not only does this demystify the idea of a black box problem, but the puzzles can break or the steel balls can be lost forever! A second note, modeling the process of making an initial hypothesis and retesting to make a revised hypothesis may be beneficial to show students that first impressions can and should be altered when more data is presented.
When all students have completed their puzzles, students observe the "real" patterns inside the puzzles. This is a fun reveal process chock full of anticipation. As each puzzle is revealed, students record the actual puzzle pattern. When students ask, "Why did we break open the black boxes?", the reply could be, "This is practice in making observations and inferences for when we apply this concept to new situations, like atomic structures." For an example of student work, view: Black Box Problems Investigation Student Work.
The EXTEND stage allows students to apply new knowledge to a novel situation. The novel situation in this case is to think about black box problems in terms of atomic structure. Atomic Shooting Gallery Investigation. This investigation uses this Flinn Scientific Kit: Atomic Target Practice. For an alternative to Atomic Target Practice, this demonstration kit uses the same ideas of indirect observation and inference: Indirect Observations and Inference - Demonstration Kit. There are several reasons the Atomic Shooting Gallery Investigation makes for a great extension.
Students practice making indirect observations and inferences in a content-specific way. The Atomic Shooting Gallery is related to Rutherford's experiments with determining atomic structure. Students gain historical perspective, recognize that the collection of data actually leads to real discoveries and test their observation and inferential skills.
Teacher Note: This kit is handy, but can be made from cardboard and wood blocks of different shapes. The cost of this kit is a good bargain for the amount of time and materials needed to make your own.
The EXPLAIN stage provides students with an opportunity to communicate what they have learned so far and figure out what it means. This stage also works for EVALUATION of student learning. For this investigation, the real test of learning is students' ability to make indirect observations and subsequent evidence-based inferences in investigations. The Atomic Shooting Gallery Investigation extension could be used for evaluation, or any other investigation that requires indirect observations could be used.
Secondarily, students can explain what they have learned by completion of the analysis questions on page 2 of the Black Box Problems Investigation. These questions help students formalize their thinking about black box problems and the benefits and limitations of models.