For the fourth consecutive year, Science on Wheels (SONW) in collaboration with Wi(PR)2EM project, offered a workshop for local math and science teachers. The event took place in Hotel Villa Antonio, Rincón, Puerto Rico on May 25th, 2013. The goal of these workshops was to provide teachers with documentation and simple demonstrations of diverse topics in the science of materials that they can, in turn, introduce into their own classrooms. Dr. Ubaldo Córdova-Figueroa and his research group provided a number of activities aiming in order to introduce the teachers to the world of colloidal suspensions. Teachers received drafts of educational modules prepared by Dr. Córdova-Figueroa and two of his graduate students as guiding materials for their classes.
The group mainly discussed ‘random walk’ in connection to the self-propulsion of objects, especially catalytically-propelled objects at small Reynolds numbers. Dr. Córdova-Figueroa provided a formal presentation in combination with two simple demonstrations performed by his graduate students. The presentation began with an introduction to random walk in general. Several common life examples were presented, in which random walk was observed. For example, atmospheric phenomena, gambling games, Brownian motion, and genetic drift, are all stochastic processes that exhibit random walk. The presentation continued, with a brief explanation of the quantitative and statistical properties of random walk. A direct connection between random walk and Brownian motion was made in order to introduce colloidal suspensions to the teachers. Finally, the idea of autonomous motion was presented to the teachers through the concepts of nanorobots and Sci-Fi movies such as Joe Dantes’ Inner Space. Current and potential applications in medical treatments and materials science were discussed in detail. At this point, the teachers were very excited about the topics and asked many questions.
For the demonstrations, teachers were divided into groups and each group was given the necessary materials for demonstrating the random walk properties using a stochastic process such as the toss of a coin. The experiment consisted of recording the final position of a particle moving in 1-D, subject to the results of each toss of the coin. If the coin landed on ‘heads’, the particle was moved to the right and if it landed on ‘tails’, the particle was moved to the left. Teachers calculated the mean final position of the particle and the mean squared average. In case of the mean, the results were very close to zero and for the mean squared average the results were close to the number of experiments performed. With these results, the teachers were able to confirm the random walk properties discussed earlier in the presentation.
In the second demonstration, the concept of catalytic propulsion of Janus particles was exposed. For this purpose, the groups were given a bottle of vinegar, a small rectangular piece of foam, an aluminum tray and sodium bicarbonate. Following the graduate students instructions, teachers built their own macroscale “nanomotor” by impregnating one half of the piece of foam into the sodium bicarbonate and submerging it into the vinegar. Teachers observed how the “nanomotor” moved, driven by the recoil of the bubbles produced in the reaction of vinegar and sodium bicarbonate. The teachers were very enthusiastic and repeated the experiment many times. At the end, Dr. Córdova-Figueroa and his graduate students left the teachers with a few unanswered questions, such as how to improve the motion and direction of the motor, with the purpose of triggering curiosity and interest among them.
This was a great opportunity to introduce teachers to the basic topics studied in our research group. As researchers, we recognize the importance of early introduction to complex concepts in science in order to motivate students to follow careers in STEM fields. For this reason, our research group is committed to the development of activities that can promote the improvement of science education in PR. At the end of the activity, an evaluation sheet was passed out to the teachers so they could rate the event. In general, the presentation was a great success with an average score of 4.6/5. Copies of the presentation were distributed for the teachers as well as copies of the draft modules of the demonstrations presented.
UCF Research group participants: Ubaldo M. Córdova-Figueroa, Luis Rivera-Rivera, Ronal De La Cruz Araujo