Straw Siphon

This activity demonstrates how to use drinking straws to create a siphon that transfers water from one container to another. It shows how gravity and air pressure work together to keep water flowing until the levels in both containers are equal.

1. Fill a tall container to the brim with water and place it next to a shorter empty container.
2. Insert one end of a straw into the tall container. Observe what happens.
3. Remove the straw, place your finger over the short end, and quickly put the other end into the tall container. Release your finger to start the flow of water.
4. Watch as water flows into the shorter container. Notice when the flow stops.
5. To extend your siphon, cut the end of one straw to a point and insert it into the end of another straw. Seal the joint with tape or modeling clay.
6. Use the extended straw siphon the same way: cover one end with your finger, submerge the other in the tall container, then release your finger.
7. Observe how much water flows into the shorter container. If the siphon stops, check the seal for air leaks and reseal if needed.

Make a Straw Siphon | STEM Activity - Science Buddies:

Water Science Experiment- Water Siphon School Science Project - Kont Kont:

📄 Make a Straw Siphon - Science Buddies: https://www.sciencebuddies.org/stem-activities/straw-siphon

• Try different siphon lengths by connecting more straws.
• Test how the height difference between the containers affects siphon speed.
• Experiment with flexible tubing instead of straws for longer siphons.
• Attempt to make a self-starting siphon without covering one end.

• Perform the activity in a tray or sink to contain spills.
• Use only clean water (never siphon toxic or unsafe liquids).
• Clean up spills immediately to prevent slipping.
• Supervise younger children to prevent messes.

• Why does the water continue to flow once the siphon starts? (Gravity pulls the water down the straw, and atmospheric pressure keeps pushing water into the straw from the tall container.)
• Why does the flow stop when the water levels are equal? (There is no longer a pressure difference to drive the siphon.)
• Can the water in the shorter container ever rise higher than in the taller container? (No, this would violate conservation of energy; the water levels must equalize.)
• What factors might make a siphon work faster or slower? (Straw diameter, height difference between containers, and length of siphon tube.)