Introduction: Glow in the Dark Oobleck
Here’s a twist on this classic classroom experiment/demo: By adding glow-in-the-dark paint and an ultraviolet light source, we can start a classroom discussion on the states of matter, non-Newtonian fluids and we can introduce fluorescence, because who doesn’t love glow in the dark stuff!
This project encourages students give into their natural curiosity, to play, to ask questions, and with the proper guidance, to make observations that will answer their questions. And bonus points, they get to make a little mess. Don’t worry, clean-up is easy.
Oobleck is named after the green sticky goo in Dr. Seuss’ “Bartholomew and the Oobleck.” Oobleck is a Non-Newtonian fluid.
Non-Newtonian fluids change viscosity when a sheer force is applied. Some materials increase in viscosity, like Oobleck. While others, like ketchup become less viscous when a sheer force is applied. Their behavior is reliant on the strain rate or how quickly you move through or around them.
Examples: Oobeleck blood, ketchup, mayonnaise, quick sand.
Newtonian Fluids have constant viscosity, regardless of the forces acting on it.
Examples: Water, alcohol.
Fluorescence occurs when light is given off by a substance after it absorbs (usually) higher energy light/shorter wavelength of light or electromagnetic radiation.
Fluorescence is used in chemistry, geology, biology and chemical sensors
W A R N I N G
UV light can cause macular degeneration, cataracts and cancer
Always wear the appropriate safety glasses when working with UV lights.
UV safety glasses are easy to find, are inexpensive and can be used as everyday safety glasses.
If the glasses are too large for small children, use a UV face shield.
Look for safety glasses listed as Ultraviolet Radiation Blocking Spectacles/Glasses/Googles/shield
Step 1: The Cornstarch
- Place ½ cup of cornstarch in a mixing cup or bowl
- The proportions of water to cornstarch is~ 1:2. One-part water to two-parts cornstarch. Scale up as needed.
- Transfer to a mixing cup or bowl.
Step 2: The Water
- Measure out ¼ cup water.
Step 3: The Paint
- Add a bit of paint to ¼ cup water.
Step 4: Mix Oobleck
- While stirring, slowly add the water to the cornstarch.
- It should be the consistency of thick pancake batter.
- If the Oobleck it is powdery, add more water.
- If it splashes add more cornstarch.
Step 5: Play
This is a hands-on experience:
- Stick your hands in it.
- Try to scoop it up.
- Slowly move your fingers through it.
- Move your fingers through it quickly and note the difference in behavior.
- Squeeze it into a ball and see what happens when you let go.
- Just play with it for a few minutes.
Step 6: UV Light Demo
- Dim the room lights.
- Put on UV safety glasses.
- Shine UV light on the Oobleck.
- Shine the light on other objects to illustrate that not everything is fluorescent.
- Introduce the idea that the kind of particles (atoms and molecules) that make up matter have different properties. Let them know that you will continue a discussion on glow in the dark matter in a later lesson.
Let me know what questions you want answered and I will try to include them in a UV light lesson Instructable.
Step 7: Dancing Monster Demo
Time (and budget) permitting:
- Remove the cover cloth from the subwoofer's speaker cone.
- Cover the speaker cone with a piece of plastic wrap or plastic bag.
- Set the volume to the lowest setting (speaker).
- Allow it to puddle.
- Once it fully puddles, ask students to describe the Oobleck.
- Set the volume to the lowest setting (on mobile device).
- As you increase the volume, watch students for any sign of discomfort from the noise. These frequency might disturb children with sound sensitivity.
- Stop or lower the volume if necessary.
- Change the frequency in small steps.
- Go up to ~60 Hz.
Step 8: Discussion Points
- What is Matter?
- Matter is anything that takes up space and has mass. Matter is the stuff stuff is made of.
- Matter can come in different forms. Let’s keep it to solids, liquids and gases for this discussion.
- Solids keep their shape. They have tightly packed particles (comparatively). The particles are bound together.
- Liquids take the shape of their container. Liquids have particles that are loosely bound together. Particles can move around in a liquid, but not as much as in gases. Liquids keep their volume.
- Gases fill their container. Particles in gases can move freely and quickly so gases do not have a definite shape or volume.
- if students have difficulty understanding what a gas is, discuss bubbles in soda, air in a balloon or soap bubble. Some students will not understand that gases have mass, discuss their experiences with air filled balloons vs helium filled balloons and why one floats.
Have students make basic observations. If they are stuck here are some questions they can investigate:
- What does Ooblek look like?
- What does it feel like?
- What does it smell like?
- What happens when you squeeze it on your hand?
- Can you pour it in a cup?
- What will happen if you hit the surface of the Oobleck with a spoon?
- What happened when you squeeze it in your hand?
Ask students how they would you classify Oobleck and why?
Runner Up in the