Ever wonder why dewdrops form? Here's a fun and simple activity to introduce your child to surface tension, and pull an awesome stunt in the process! Park science, part magic, this is a great way to get your child excited about the way things work.
What You Do:
- Drape the handkerchief over the glass, making sure that you push the center of the handkerchief down into the glass.
- Fill the glass three-quarters full with water, by pouring all the liquid into the middle of the handkerchief.
- Stretch the handkerchief tightly across the surface of the glass, then grip the ends of the handkerchief at the bottom of the glass.
- Place one hand over the mouth of the glass and turn it over with the other hand.
- Pull the lower hand away from the glass (slowly) and the water should stay in the glass!
- Next, place your hand over the mouth of the glass and turn the glass right side up again. Remove the handkerchief from the glass and pour the water back into the container.
The water didn’t leak because it went through the handkerchief as it was poured into the glass. The microscopic thread webbing in the handkerchief literally disappeared when the cloth was stretched tightly across the mouth of the glass. This action allowed the water molecules to bond to one another, by the phenomenon known as “surface tension.” Surface tension prevented the water from seeping through the handkerchief!
Mike is a 20-year veteran science teacher, and runs an online business (www.scienceinabag.com). Over the years Mike has studied trends in science, education, and finance, conducting research, developing programs, and writing articles on these topics.