Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.
Ages 5-7: Draw & tell
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Siphons · Ages 5-7
Watch the Water Climb
Look at your tube and jars, then draw and circle.
1. Draw the two jars and the tube. Draw an arrow showing which way the water moved.
2. Which jar did the water go into?
◯ The high jar◯ The low jar
3. Did the water go up over the edge of the jar?
◯ Yes◯ No
4. When the low jar was lifted up high, the water...
◯ went back the other way◯ went the same way◯ stopped
5. One word for how the water moved:
Ages 8-10: Predict, test & record
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Siphons · Ages 8-10
Siphon Test Lab
Make a guess, test your siphon, and write down what happens.
1. Predict: if you leave the siphon running, the high jar will...
◯ empty completely◯ stop before it is empty◯ never stop flowing
2. Put the low jar at three different heights (always lower than the high jar's water). How fast does the water flow?
Where the low jar is
Fast, medium or slow?
What I noticed
3. As the two water levels got closer together, the flow got...
◯ faster◯ slower◯ stayed the same
4. What did you find out about which way a siphon flows?
5. Why do you think the tube has to be full of water before you start?
Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Siphons · Ages 11-14
Explaining the Siphon
Use your siphon and the ideas in "What's going on?" to explain and test it.
1. Use the words gravity and air pressure to explain why water climbs up out of the high jar.
2. What must be true for a siphon to keep flowing?
◯ The outlet end is lower than the water surface in the high jar◯ The bend of the tube is lower than both jars◯ The low jar must start empty
3. You want to test whether the height difference between the jars changes the flow rate. Name what you change, what you measure, and two things you keep the same.
4. Design a fair test of one other variable (tube length, how high the bend goes, or tube width). Time how long it takes to fill one cup.
Trial
What I changed
Seconds to fill one cup
5. A siphon lifted about 18 ft (5.5 m) still flowed. Why can't a water siphon go higher than about 10 m (34 ft)?
6. Where else are siphons used?
Answer guide for grown-ups
Homemade Science with Bruce Yeany · Siphons · Answer guide
Answer guide
Ages 5-7: Watch the Water Climb
Open answer: look for effort and careful observation.
The low jar
Yes
went back the other way
Any fair word, such as up, over, down, fast or slow.
Ages 8-10: Siphon Test Lab
Stop before it is empty: it stops when the two water levels match, or when the high jar's water drops below the end of the tube.
Open answer: look for effort and careful observation.
Slower
It always flows toward the lower water; when the jars swap heights, it turns around and flows the other way.
A big air bubble at the top stops it. The falling water in the long side lowers the pressure at the top, and air pressure pushes more water up; air in the tube breaks this.
Ages 11-14: Explaining the Siphon
Gravity pulls the water down the long side of the tube, leaving lower pressure at the top of the bend. Air pressure pushing on the water in the high jar is now bigger, so it pushes water up into the tube to replace what left.
The outlet end is lower than the water surface in the high jar
Change: the height of the low jar (the drop). Measure: flow rate, e.g. seconds to fill one cup. Keep the same: tube length and width, the liquid, the starting water level in the high jar, the same cup.
Open answer: look for effort and careful observation.
Air pressure can only push water up about 10.3 m (33.9 ft). Near that height a near vacuum forms, gas bubbles come out of the water (cavitation), and the siphon stops.
Cleaning aquariums, irrigating crops, flushing toilets, the Tantalus cup; siphons also occur in nature.