Build and test simple water channels using gutters, plastic bottles, and sand to observe how flow speed, obstacles, and slope affect moving water.



Step-by-step guide to Practice Your Flow
Step 1
Gather all your materials and bring them to a clear workspace on the floor or a table.
Step 2
Spread the towel or place the tray under your workspace to catch water spills.
Step 3
With an adult's help cut the plastic bottles in half to make open troughs for extra channel pieces.
Step 4
Line up the gutter sections or bottle troughs end-to-end and tape the joints so you have one long channel.
Step 5
Prop one end of the channel on a stack of books to make a gentle slope and make sure it is steady.
Step 6
Pour a thin layer of sand into the bottom of the channel to make the channel bed.
Step 7
Put a piece of tape at the top of the channel to mark your starting line.
Step 8
Place one small pebble or toy in the middle of the channel to act as an obstacle.
Step 9
Measure a set amount of water with the measuring cup and keep it ready beside the channel.
Step 10
Ask an adult to get ready to start the timer when you begin pouring the water.
Step 11
Pour the measured water onto the start line and let it flow down the channel.
Step 12
Ask the adult to stop the timer when the last bit of water reaches the end of the channel.
Step 13
Write the time in your notebook and jot one short note about what you noticed in the flow.
Step 14
Repeat the whole test two more times changing only one thing each time (for example make the slope steeper or move or remove the obstacle) and record each time.
Step 15
Share a photo and your results about how slope and obstacles changed the flow on DIY.org.
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!


Help!?
What can I use if I can't find gutter sections or don't want to cut plastic bottles?
Use a split paper-towel tube wrapped in waterproof tape or a folded cardboard chute lined with aluminum foil as a substitute for gutter sections or cut plastic bottles, then tape the joints and proceed with the sand and water tests.
Why is my water leaking out between taped joints or the channel keeps slipping, and how do I fix it?
If water leaks at the taped joints or the channel slips, press the joints together and reinforce them with waterproof duct tape, add extra tape under the channel where it rests on the stack of books, and stabilize the slope with more books or clamps so the measured water reaches the end.
How can I adapt this activity for younger or older kids?
For younger children, pre-cut the plastic bottles, use smaller measured pours from the measuring cup, and time with a simple 'start/stop' adult help, while older kids can change the slope more precisely, vary water volume, record times in the notebook, and analyze how the obstacle altered flow.
What are fun ways to improve or personalize the experiment after the basic three trials?
Try coloring the water with food dye to visualize currents, add multiple pebble obstacles or branching channels, record and graph each trial's time in your notebook, and then share a photo and results about slope and obstacles on DIY.org.
Watch videos on how to Practice Your Flow
Facts about water flow and simple engineering
🌊 Open-channel flow (rivers, gutters, channels) has a free surface exposed to air, unlike closed-pipe flow.
🛠️ Rain gutters were invented to protect buildings by channeling roof water safely away from foundations.
🏖️ Sand both slows water and moves with it — flowing water sorts grains so bigger ones settle first.
💧 Steeper slopes make water flow faster — even a small tilt can turn a trickle into a rush!
🌀 Tiny obstacles create eddies and calm pools where sediment settles and small animals can hide.


Only $6.99 after trial. No credit card required