Traveling Water
Lesson Plan Amount of time Demo takes:​
1-2 min
Try this at home!
Materials
● Identical wide-brimmed plastic cups (2)
● Water
● Cotton-based string
● Food coloring
● Masking tape
● Scissors
● Bucket for water, bucket for waste
Setup instructions
1. Cut a piece of string (about 1.5 foot long).
2. Dip the entire string in water and remove.
3. Tape one end of the string at the bottom of one of the cups.
4. Fill the other cup halfway with water and add some food coloring.
SAFETY!
Clean up water spills immediately to prevent water-related accidents.
Lesson’s big idea
● Adhesion: ​
Attraction process between dissimilar molecules, resulting in
the water molecules “sticking” to the surface they are touching. In this
case, the water initially adheres to the string.
● Cohesion: ​
Molecules the are alike tend to stick together, making water
molecules “stick” to one another. For our example, the water molecules
from the cup cling to the ones on the string.
● These two properties allow the water to “stick” to the string and flow
down into the other cup.
1/2 Background information
● Water is strongly attracted to cotton, which is why it is used for products
like mops or towels. Materials such as cotton become wet when water
bonds or adheres to the surface and spreads through the fibers of the
fabric.
● For comparison, water does not have a strong attraction to nylon, which is
why nylon rain coats repel water. Nylon has stronger bonds between it’s
molecules as well making it difficult for water to penetrate the material
and instead forming droplets.
Instructional Procedure
1. Use your thumb to hold the loose string end in the cup filled with colored
water. Take one cup in each hand and pull the string taut between them,
holding the water filled cup higher than the empty cup.
2. Slowly pour the water “down” the string into the empty, waiting cup.
3. If possible watch listed video for a clear example of the technique used.
Assessment/sample questions you can ask
● Discuss ideas like adhesion and cohesion
● Why doesn’t the water just pour straight down (following gravity)?
Clean Up
Between demonstrations, pour colored water back into the now empty cup.
Clean up and change materials as needed. When completely finished, gather all
the materials listed for this demo and make sure everything is accounted for. If
something was used up, broken or damaged, let someone know so it can be
replaced or fixed.
References
http://www.youtube.com/watch?v=kUL_317rptE
Next Generation Science Standards
5-8 Content Standard B: Physical science, transfer of energy, motions and forces
2/2