Properties of water are fun to teach. A few simple activities can drive home important science concepts like evaporation, cohesion, adhesion, water as a solvent, and capillary action. Read on for ideas for your classroom.
Ms. Sneed Plans to Teach Properties of Water
Our favorite fourth grade teacher, Ms. Sneed, opened her science cabinet and gathered a variety of simple materials for a week of water science experiments.
“I’ll just need to grab a pie plate from home,” she said to herself. “Otherwise, we’re ready to explore properties of water.”
Begin with an Evaporation Experiment
On Monday, Ms. Sneed’s students set up an evaporation lab.
“To ensure a fair test while using the scientific method,” she said, “you’ll control all but one variable.”
Each group measured 50 ml of water into two plastic cups. The first two science lab groups placed one of their cups in a sunny location and another in a dark place. The second two groups added salt to one cup but not the other. Finally, the third set of groups covered one cup but not the other.
“We’ll check these later in the week to see how much water has evaporated.”
Explore Two Properties of Water
On Tuesday morning, the students ran to their evaporation experiments to see what had happened. Unfortunately, they couldn’t see any changes.
“Give it time,” said Ms. Sneed. “Today and tomorrow we’ll take a look at two properties of water: cohesion and adhesion.”
“Huh?” one girl blurted out.
“I know,” Ms. Sneed replied. “New vocabulary. But really we’re just exploring water’s stickiness.”
The first set of activities involved cohesion.
First, Ms. Sneed did a demonstration. “How many of you think this paper clip will float?” A few hands raised tentatively. The rest of the class shook their heads.
Then their teacher slowly laid the paper clip on top of the water – and it floated!
“Why does this paper clip float?” she asked. After a bit of discussion, the class landed on the idea that the surface of the water somehow held it up.
“You’re right. Water molecules stick to one another. We call this cohesion. Because of cohesion, surface tension occurs. Just think about what happens when someone jumps flat-out into a swimming pool…”
“Belly flop!” a few kids called out.
“Next,” Ms. Sneed said, “you will play with some water.” She quickly distributed wax paper, small containers of water, eyedroppers, toothpicks, and pennies. Following their lab sheets, the students placed drops of water onto the wax paper.
First, they used their toothpicks to split the drops into smaller and smaller and smaller droplets. Next, they pulled drops of water close to other drops.
“Ms. Sneed! These drops are magnetic,” one student said. “When I put them near one another, they attract and pull together.”
The teacher smiled. “Simple hands-on science activities can drive home complicated concepts,” she said to herself.
For the second activity, kids used the eyedropper to place drops of water on a penny. As Ms. Sneed walked around the room, she heard lots of discussion:
“Twenty-six, twenty-seven, awww!”
“How many did you get?”
“Let’s try it again!”
The following day, Ms. Sneed’s class worked on adhesion. First, they simply looked at the surface of water in a glass graduated cylinder.
The first child to try it peered through his glasses. “Oh wow, it’s curved.”
Second, they bent five toothpicks in half and organized them in the shape of a star. As they dropped water into the center of the star, it filled in, but surprisingly the tips stayed together.
Ms. Sneed saw one girl dip her finger into a container of water, hold it up, and watch as two drops slowly dripped off. “My finger is still wet,” she said.
“Yep. Adhesion,” her teacher responded.
Examine Water as a Solvent
On Thursday, Ms. Sneed set up another demonstration. After pouring about an inch of water into a pie pan, she set it under the document camera so everyone could see. Then she dropped in four colored candies.
“Whoa! Look at that!” In no time at all, the candies had begun to dissolve.
Next, Ms. Sneed asked the science groups to measure 50 ml of water into a cup. Then they poured in 10 cc of salt and stirred.
“I can’t really see the salt anymore,” one child remarked.
After the salt had dissolved, kids measured the salt water. “Hmm,” said a boy with curly hair, “this water is less than 60 ml. How can that be?”
Once her students had completed their lab sheets, Ms. Sneed debriefed them. “When a substance dissolves, it becomes evenly distributed. Therefore, it may fill in spaces between water molecules.”
“Yeah, but how do we know that the salt is still there?” asked a girl at a back table.
Ms. Sneed looked around the room. “Well, if you taste the water, you can taste the salt,” a student suggested.
Their teacher took one cup of salt water and poured it into a pie pan. “We’ll let this set for a few days. Once the water’s evaporated, we’ll see what remains.”
Have Some Fun with Capillary Action
On Friday, Ms. Sneed stood in front of her class holding a stalk of celery. “What will happen if I put this celery into that cup of colored water?” she asked.
“Everybody knows that,” mumbled a girl in the front row. “We’ve done that experiment every year since first grade.”
“I figured,” Ms. Sneed replied. “But just for fun, let’s do it again.” She plopped the celery into the water.
“So, since you’ve already done it, what happens?”
“The veins suck up the colored water,” offered the girl in the front row.
“Anyone know how?” She looked around the room. No takers. “Okay, today we’ll set up a few more labs to explore capillary action. As you complete the activity on your lab sheets, I’ll set up anther demonstration.”
More Capillary Action
While her students set up a chromatography activity, Ms. Sneed placed three cups of water near one another. She put yellow food coloring in the cup on the left. Then she put blue food coloring in the cup on the right.
“Okay, everyone, stop what you’re doing for a minute,” she said. As they watched, she rolled up two paper towels. She put one end of the first paper towel into the yellow water and the other into the clear. Then she placed one end of the second paper towel in the clear and the other end in the red. “As you observe your coffee filters,” she said, you can also come over here and see what’s happening.”
For the next 20 minutes, kids moved back and forth between their lab groups and the paper towel set-up.
At first, students made simple observations like “Look, the paper towels are absorbing the water.”
Then things became more exciting. “Oh my goodness! The dot of ink on the coffee filter is separating into different colors!”
And even more exciting. “What? The water in the middle cup has turned green! Hey, how did that happen?”
Once the excitement cleared up and everything was cleaned up, once again, the class debriefed. “The forces of adhesion and cohesion,” summarized Ms. Sneed, “allow water to defy gravity and move into porous materials. While we know this as absorbing, scientists call it capillary action.”
Expanding the Study of Water
Over the years, Ms. Sneed added more water science activities to her curriculum. In addition to properties of water, she also taught about the hydrosphere, the water cycle, waves and currents, as well as water pollution. Each facet of hydrology helped her kids conceptualize science concepts. And they had a lot of fun along the way!
Over the course of her career, Ms. Sneed realized that there were 6 steps to enjoy teaching. In order to survive, she had to organize, plan, and simplify. Then, to thrive, Ms. Sneed needed to learn, engage, and finally – dive in! Follow the Fabulous Teaching Adventures of Ms. Sneed and learn how you can enjoy teaching too.