Halloween STEM Challenges: chemistry of color, vision, and slime

By: Meghan Thoreau, OSU Extension Educator

October’s STEM Club

We thought we’d take advantage of the spooky mystery themes of Halloween and challenge our students to become science detectives, experimenting with hands-on activities involving chromatography, perception of vision, and phosphorescent slime chemistry.

Chromatography

The students became CSI lab technicians, tasked with solving a who-done-it pumpkin theft. All that was left at the scene of the crime was a letter demanding cookies! No finger prints were found, but six suspects where brought in for questioning and all six had different black markers on their person. The marker evidence was tagged and brought to the CSI lab along with the random letter for further analysis. Marker samples were taken and a chromatography test was performed by our young lab technicians.

Chromatography is a laboratory technique for the separation of a mixture (more specifically separation of molecules) and in our case black marker ink molecules. The ink was dissolved in a water solution process of a mobile to stationary phase, revealing distinct ink-finger prints for comparative analysis against an ink sample taken from the random note. The students discovered different ink molecules travel at different speeds, causing them to separate and reveal distinct color patterns that could help identify the pumpkin thief from the six suspects.

People don’t often pick up a marker or pen and think of molecules,  but ink and paints are made up of atoms and the molecules, like everything, follow rules. Ink and paints follows the standard CPK rule, which is a popular color convention for distinguishing atoms of different chemical elements in molecular modeling (named after the chemists Robert Corey, Linus Pauling, and Walter Koltun). Basically, certain elements are associated with different color. For example,

  • Hydrogen = White
  • Oxygen = Red
  • Chlorine = Green
  • Nitrogen = Blue
  • Carbon = Grey
  • Sulphur = Yellow
  • Phosphorus = Orange
  • Other = Varies – mostly Dark Red/Pink/Maroon

PERCEPTION OF VISION

Persistence of vision refers to the optical illusion that occurs when visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye. The discovery was first discussed in 1824 when an English-Swiss physicist named Peter Mark Roget presented a paper, “Explanation of an Optical Deception in the Appearance of the Spokes of a Wheel when seen through Vertical Apertures” to the Royal Society in London. Shortly after, in 1832, a Belgian physicist Joseph Plateau built a toy that took advantage of the optical illusion trick. (Photo below source: http://streamline.filmstruck.com/2012/01/07/the-persistence-of-persistence-of-vision/)

The toy made images move independently, but over lapped them or when placed in a series made them look as if they were walking, running, juggling, dancing. This concept soon laid the foundation to early film making. (Photo below source be: http://1125996089.rsc.cdn77.org/wp-content/uploads/2011/12/persistence-of-vision-transit.jpg)

The students learned how our eyes report basic imaginary back to the brain, or rather how our eyes perceive shapes, their motion, and their relative position from other objects. The students discovered that eyes are not simple windows to the world. Eyes do not see what is, but instead see approximations.

PHOSPHORESCENT SLIME

The students learned how different objects glow in the dark. First, students learned that heat is a good emitter of light, such as a fire or an old-fashioned light bulb, but heat isn’t always required to make something appear to glow. For example, bedroom glow-in-the-dark stickers, glow sticks, or fireflies do not require heat. The stickers and even certain types of rocks, like the Bologna Stone, require several hours of light to charge them in order to later glow. But glow sticks and fireflies, do not require heat or light, but instead deal with chemistry where two different elements are mixed together to make a ‘luminescent’ compound.

We talked about phosphorescence and the process in which energy absorbed by a substance is released slowly in the form of light. Unlike the relatively swift reactions in fluorescence, such as those seen in a common fluorescent tube, phosphorescent materials “store” absorbed energy for a longer time, as the processes required to re-emit energy occur less often.

Finally, we let the students become chemists and make their own phosphorescent slime for later glow in the dark fun after the compound was charged by light. The young chemists used measuring devices to concoct their spooky slime recipe.

Make another batch at home with your young chemist:

  1. Add 20.0 mL of glue to cup
  2. Add 15.0 mL of water to cup
  3. STIR!
  4. Drop of preferred food coloring
  5. STIR!
  6. Add a drop of glow in the dark phosphorescence paint
  7. Add 12.0 mL of BORAX solution
  8. STIR! It will be runny until you take it out of the cup and start to play with it.

Next month we will be challenging our STEMist in Mind and Body Challenges! Stay tuned to learn more about November’s STEM adventures.

Developing the 21st Century Skillset through Learning and Building Electric Circuits

By: Meghan Thoreau, OSU Extension Educator

Our STEM Club focuses on developing a lifelong learning mindset that supports our youth in exploring exciting STEM careers and promoting an engaged life. The 21st Century Skillset is a cycle of applied learning, critical thinking, collaboration, and learning by doing. Our STEM Challenges build foundational literacy skills, competencies, and character qualities that are critical to our day-to-day lives, how youth look at complex challenges, and how youth deal with their changing environment while retaining a growth mindset of persistence and grit. Below is an image that highlights important life skills that students and parents can work towards attaining.

September’s STEM Club: Day 1

Wondering what a club day looks like? Here’s a quick video, STEM in action. Try to listen to the communication going on, productive chaos.

Make sure to like us on Facebook, OSU Extension posts STEM Club Albums for parents who want to stay engaged!

September focused on two hands-on electric circuit challenges. The first engages students in designing and building an LED Display (light emitting diode) to light up their initials. Students learn basic electrical design components, how to read an electrical schematic, how to interpret an engineering data sheet, how to design the circuit, and finally how to build a LED Display Board! OSU Professor, Betty Lise Anderson, of The OSU Department of Electrical and Computer Engineering came down from campus each week to teach the electrical outreach activity she developed. Many thanks to her and her STEM team! Dr. Anderson is amazing and generous with her time, knowledge, and materials. To learn more about Dr. Anderson or the department click here. Below is an image of the LED Display and a sheet explaining how to read the pin connection table, and understanding an electric schematic and basic electrical symbology. Each student determines which of the 16 segments of the LED display they need to connect resisters in their bread board.

Mentorship Benefit

Our program benefits immensely not just by our STEM Educators and OSU Extension’s partnership, but by the high school mentors that come and make the difference in young people’s lives by offering stable relationships to support students’ academic and social development. Below one high school mentor, Summer, came to assist despite it being Homecoming week. She received a round of applause by our students as she walked into the classroom!

Teamwork

Below we have a short video that allows you to see first hand students building an LED Display, but also demonstrating team building skills – one elementary student takes a moment to help a fellow STEMist troubleshoot the correct wire connection. May seem small, but this is an extremely important skill for real world success.

 

September’s STEM Club: Day 2

Our second STEM challenge took the knowledge the students learned about electric schematics and circuits and applied it to building a LED flashlight (take home project). The challenge involved basic materials, an cardboard box, copper wire, a battery, a resister, and a LED (light omitting diode), but it also introduced a switch.

Inside the Flash Light

 

Future Engineers! O-H-I-O

 

October’s STEM Club will involved a little Chemistry in Action!