In the Classroom

This is a relatively simple and easy experiment to set up and is relatively low in startup costs. The most important thing is that this experiment is fun for all ages! The swollen beads might be swallowed by young children and then they would grow in their stomachs or throat causing the beads to potentially block breathing. The seeds should not be given to kids. In addition, along the growth of the beads, the spheres can have a size that can result in them being a potential choking hazard. Do not give either the seeds or the spheres to kids. Teachers should use different colored dyes to turn the ghost eggs into different colors for the kids to see. Also if the teacher can utilize a black light and fluorescein dye, they could turn off the lights and create glowing ghost eggs! Science Discipline: Chemistry Topics: Absorbance, Refractive Index, Hydrophilic polymers. Activity Title: Ghost Eggs Materials:
  • 4-6 plastic cups.
  • 3-4 plastic bowls.
  • Multi colored food dye. (Blue, green, purple, orange, red, fluorescein etc.)
  • 50 grams of Ghost eggs. (about 3000 spheres 1 cm big)
  • Room temperature water. (Enough to fill the cups and bowls about ¾ full.)
  • Black light (if using the fluorescein dye)
Procedure:
  • Fill the cups or bowls about three fourths to the top with room temperature water.
  • Next place about 8-10 drops of your choice of food coloring dye into the water, and leave one cup with no food coloring added.
  • Next, measure across the middle of the smaller beads with a ruler and record the diameter before placing it in the water.
  • Fully soak the small round beads in the water and watch and observe the size changes over the next 3-4 hours.
  • Teachers may want to start the soaking of the beads overnight in order to get bigger beads for the kids to play around with.
  • Once the ghost eggs have finished growing in size have the kids dunk their hands in the water to grab the ghost eggs and measure the diameter of their eggs.
  • Next have them grab a ghost egg from the cup without any dye and then place their eggs back in the water and watch them disappear right in front of their eyes!!
  • Try making the eggs fluorescent in a black light by adding a dye called fluorescein. The ghost eggs will start to glow!
  Inquiry Questions:
  1. Have the kids make a prediction on what will happen when the beads are placed in water. Have them propose a hypothesis and design an experiment to test their hypothesis. A data table can be collected of size vs. time which can then be graphed. Students can then analyze their data to see if the hypothesis was supported.
  2. Placing the fully-grown beads in salt water can cause water to come out of the swollen beads. You might have the kids make a prediction of what they think will happen if they put the swollen beads in water containing salt and then have them make a hypothesis, design an experiment, and test their hypothesis. Different concentrations of salt in water can cause this shrinking process to be faster or slower.
Questions:
  • Ask the kids why they think the eggs are growing while they are soaking in the water bath.
  • Ask the kids what they think will happen to the ghost eggs if they were left out of the water for a long period of time. Would they shrink or stay the same size?
  • Explain to the kids about how water bends light (like a straw in a cup of water) and then ask them why their eggs disappeared when they are placed back in the clear water.
Explanation:
  • The eggs are growing because they are water absorbent polymers and they love to be in water due to the hydrophilic nature of the compounds.
  • If the ghost eggs are left out of water for a sufficient amount of time the water inside of them will begin to evaporate and this will cause the ghost eggs to shrink in size.
  • The eggs disappear in water because they are mostly filled with water and they have the same refractive index of light. This bends the light around the ghost eggs which is why they appear invisible.