Students work as engineers to learn about the properties of molecules and how they move in 3D space through the use of LEGO® MINDSTORMS® NXT robotics. They design and build molecular models and use different robotic sensors to control the movement of the molecular simulations. Students learn about the size of atoms, Newman projections, and the relationship of energy and strain on atoms. This unique modular modeling activity is especially helpful in providing students with a spatial and tactile understanding of how molecules behave.
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- International Technology and Engineering Educators Association: Technology
- F. Knowledge gained from other fields of study has a direct effect on the development of technological products and systems. (Grades 6 - 8)  ...show
- New York: Science
- Key Idea 3: Matter is made up of particles whose properties determine the observable characteristics of matter and its reactivity. (Grades 9 - 12)  ...show
- Next Generation Science Standards: Science
- Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering. (Grades 9 - 12)  ...show
- Design a LEGO robot.
- Program a robot with LEGO NXT MINDSTORMS software.
- Program light and ultrasonic sensors to detect different colored and sized model molecules.
- Program the response from the light and ultrasonic sensors to the display screen.
- Explain steric hindrance of molecules and terms such as Newman projections, staggered and eclipsed.
- Describe how energies relate to staggered and eclipsed.
- LEGO MINDSTORMS NXT robot and software, such as the LEGO MINDSTORMS Education NXT Base Set and Software Pack (5003404) available for $376 at https://shop.education.lego.com/legoed/education/NXT/NXT+Base+Set+and+Software+Pk/5003404&isSimpleSearch=false
- LEGO NXT Intelligent Brick (for example, part #9841 for $149.99, available at http://shop.lego.com/en-US/NXT-Intelligent-Brick-9841?CMP=AFC-BP6648365778&HQS=9841)
- Molecular modeling kit to build atoms with bonds (for example, Molecular Visions: The Flexible Molecular Module Kit, part #595 for $23, available at https://www.etsy.com/listing/99279210/molecular-visions-the-molecular-model)
- light sensor (included in the molecular modeling kit)
- ultrasonic sensor (included in the molecular modeling kit)
- 3 plastic sticks (included in the molecular modeling kit)
- 2 plastic balls of the same size (0.5 inch to 3 inches diameter; included in the molecular modeling kit)
- 1 Styrofoam ball, larger in size than the two plastic balls (such as 4 inches in diameter; available at arts and crafts stores)
- 2 sheets of the same colored construction paper, enough to cover a Styrofoam ball
- tape or glue, to adhere the paper to the ball, and the sticks to the motors
- Molecular Modeling Worksheet, one per person
- computer, loaded with NXT 2.1 software
- LEGO MINDSTORMS NXT data logging program (comes with the LEGO NXT programming software)
- ChemDraw software (download a free trial version from CambridgeSoft at http://scistore.cambridgesoft.com/ScistoreProductPage.aspx?ItemID=5561; refer to the CS ChemDraw User's Guide at http://www.cambridgesoft.com/support/DesktopSupport/Documentation/Manuals/files/chemdraw_9_english.pdf)
- Note: one computer per group is ideal, but if only one computer is available, then conduct the activity with the entire class a group.
|atom:||A basic unit of matter comprised of a dense nucleus with protons + neutrons and a cloud of electrons surrounding the nucleus.|
|eclipsed conformation:||The maximum energy conformation in which the adjacent atoms are in the closest proximity to one another.|
|Newman projections:||Used to visualize chemical conformations of carbon-carbon bonds with the front carbon represented as a dot and the back carbon represented as a circle.|
|staggered conformation:||The energy minimum conformation, in which the substituents have the maximum distance from one another and require torsion angles of 60°.|
|steric hindrance:||When two atoms in a molecule try to fight for space and face overlapping electron clouds, which causes an increase in the energy for the molecule.|
Before the Activity
- Gather materials and make copies of the Molecular Modeling Worksheet.
- Divide the class into groups of five students each.
- Ask students to make predictions, as described in the Assessment section.
With the Students—Design and Build the Robot
- Have student groups brainstorm several design ideas for their molecular modeling robots and make sketches. They could use the design shown in Figure 1 as the base of the design and brainstorm ideas for how to add the two sensors, which could be placed in numerous locations in order to control the speed of the molecule movement. Once designs are finalized, have them (or the teacher) pull together all the needed parts.
- Suggest that they begin by creating the backbone of the robot using long LEGO beams and small motors (see Figure 2, left).
- Attach the plastic sticks to the motors using tape or glue (see Figure 2, left). (Note, the sticks provided in the modular modeling kit already come with 30°, 60° and 90° angles.)
- Cover the Styrofoam balls with colored construction paper. Use enough tape to make sure the paper covers the balls since the sensors only recognize a Styrofoam ball if the paper is around it. Make sure that two of the three balls are the same size and color, and smaller in size and different in color from the third ball. Make two sets of these balls and attach them to the sticks (see Figure 2, right).
- After the students make their molecular modeling robots, have them show their designs to the class for critiques from their colleagues (for example, unstable construction). Once they receive critiques, they improve their robots before moving on.
- Add the sensors to the set-up, so the balls move just below the sensors (light and ultrasonic) and can get detected by the sensors. On the bottom, place a motor with stick and balls attached, but no sensors. See Figure 1 for generally how the set-up should look. Have students attach the ultrasonic sensor to the robot's port 4 and the light sensor to the robot's port 3. Then have students go to the view function on the NXT brick to verify whether the sensors are working (see Figure 3). (Note: the light sensor detects color changes; the ultrasonic sensor detects distance changes. Students can figure out where the sensors go by whether the sensors are able to detect the balls or not. Through experimentation, they can optimize the sensor positions.)
- With functioning sensors, hold another class critique: What is working? What is not working? (For example, poor sensor locations that do not enable controlling of the molecule movement or the ball is not completely covered by construction paper so the ultrasonic sensor cannot see it.). Make improvements before moving on.
With the Students—Program the Robot
- Have students program their robots to detect the different sizes of atoms with the ultrasonic sensor, and staggered (atoms/balls are 30˚ away from one another) and eclipsed (atoms/balls line up with one another) conformations with the light sensor and the ultrasonic sensor. Students must do a bit of trial and error in order to learn how to do this. Use the NXT guide to help with this programming.
- Use the ultrasonic sensor in the common palette (see Figure 4) to recognize when the large Styrofoam ball is close or far away. Make the motor move faster when the large ball is closer to the ultrasonic sensor or slower when the larger ball is further away from the ultrasonic sensor.
- After students are able to demonstrate to their classmates that they can operate the ultrasonic sensors, have them try programming the light sensors so they recognize the different ball colors (see Figure 5). For example, perhaps program the motor to move at different speeds when it sees a certain color.
- Once students have grasped programming the light sensor, they can begin to think about how to monitor the output of the sensors via data logging. They can use trial and error to figure out how to set up their experiments. They can select the sensor they want to monitor and look at the output of the sensor at certain time points, using the data logging program. Refer to the Figure 6 image of the data logging program for the fields to use to set up an experiment to conduct.
- While students are using their robots and moving the molecules around, teach the vocabulary words. Suggest that students look at the worksheet questions and start thinking about the answers. Refer to the Figure 7 images for help in understanding some of the vocabulary terms.
- Teach students about ChemDraw to assist in their understanding of the models with the aid of this application. Have students first explore the ChemDraw application, and then learn how to create the models in 3D space using the tutorial found at http://www.camsoft.co.kr/services/documentation/chemdraw_8_english.pdf. Also refer to the ChemDraw guide. Creating molecules is a trial and error process. Suggest they explore the ChemDraw buttons and try to create an ethane molecule (see Figure 8).
- Once students have created their molecules, review the definitions of staggered and eclipsed conformations. Refer to the Figure 9 images to assist in making the connection between the 3D ChemDraw program and the 3D robotic simulations. Expect students to be able to visualize the staggered and eclipsed conformations on the robot when it is moving.
Activity Embedded Assessment
- For advanced students, work with them to create the robot program in advance of conducting the main part of the activity. Or, once students complete their finalized (class-approved) robot designs, show them the molecular model robot and how it works with the sensors, and give them time to experiment, perhaps creating their own robot programs, as described in the Activities Extensions section.
Jennifer S. Haghpanah, Jill Fonda, Noam Pillischer, Jin Kim Montclare
© 2013 by Regents of the University of Colorado; original © 2011 Polytechnic Institute of New York University
AMPS GK-12 Program, Polytechnic Institute of New York University
Last modified: March 31, 2015