These chemical change labs explore five types of evidence: bubbles, color, heat, odor, and light. First, kids experiment with physical change. Then they launch into reactions that create new substances.
Mr. Grow Plans His Physical and Chemical Change Unit
Our favorite fifth grade teacher sat at the side table with his teaching partner. “Today,” he said, “we’ll continue planning our matter activities. This week, our kids are getting an introduction to matter. Next up, physical and chemical change.” He pulled up the standard on his computer and read it aloud:
NGSS 5-PS1-4 Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
“Actually,” said Mrs. Washington, “I’ve been giving this one some thought. Obviously, kids must discriminate between physical and chemical changes. But how? So I did a little research. As it turns out, reactions provide evidence. Through my investigation, I found five types: bubbles, color, heat, odor, and light.”
“Hmm,” Mr. Grow said, “Can kids do an experiment for each one?”
Mrs. Washington’s eyes twinkled. “I already found some physical and chemical change activities.” She beckoned to Mr. Grow, and he moved around to look at her laptop screen.
“Six labs illustrate specific changes. They seem wonderful to me. However, I’d like to try them out. Let’s split them up. Tomorrow we’ll meet again. Then we can try each lab ourselves.”
Physical Change
As promised, the two teachers met the following day. In their arms, each carried a bag of materials. After walking to the side table, they organized everything. Finally, they were ready to share.
“First,” said Mrs. Washington, “let’s try the lab on physical changes.
“For states of matter, they’ll just observe an ice cube. To explore mixtures, they’ll stir together two groups of small items. For example, lima beans and marbles. Then for a solution, they can stir together sugar and water. For all of these activities, kids will work in their science lab groups.”
“How will they respond?”
“For every activity in this sequence, kids fill out a lab sheet. In each, they discriminate between physical and chemical change. You know, was a new substance created? To prove it, they explain the evidence. And we’ll be giving them plenty of it!”
Chemical Change with Bubbles as Evidence
After Mrs. Washington finished, Mr. Grow pointed to his first set-up. “In this lab, kids experiment with vinegar and baking soda.”
Then he demonstrated. With an eyedropper, he added just a few drops of vinegar to the white powder. Soon, bubbles fizzed in the cup. “Here, kids see the first type of evidence of chemical change. If they look carefully, they can also see that the baking soda has changed. A new substance has been created.”
Mrs Washington nodded.
With Color Evidence
Mr. Grow continued. “I wasn’t sure the next experiment would work.”
As he spoke, he added red food coloring to three cups of water. Then he added different liquids to each one.
“First, I’ll add about 20 drops of vinegar to this cup.” Although Mrs. Washington watched carefully, nothing happened.
“Second, I’ll add 20 drops of hydrogen peroxide to this one.” Again, nothing happened.
“Third, I’ll put 20 drops of bleach in the last cup.” At first, nothing happened.
Then – “Oh wow!” Mrs. Washington exclaimed. “The color is fading! For some reason, I expected one of the cups to turn blue or something.”
Mr. Grow laughed. “No, in this lab, evidence of chemical change is color. But here, kids observe loss of it.”
“This is a good one,” Mrs. Washington said. “However, I don’t trust kids to work with bleach. Therefore, we’ll do this as a demonstration.”
With Heat Evidence
“Wait until you see this experiment,” Mr. Grow said. Quickly, he moved to his third lab set-up.
“First, I fill this cup about one-fourth of the way with hydrogen peroxide. Second, I record the temperature.”
He put a thermometer into the liquid and waited a few seconds. “About 71 degrees Fahrenheit.”
“Next, I add a teaspoon of yeast.” Immediately, it began to bubble.
The two teachers stared at the thermometer. “75.3, 78.2, 80!” Over the next few minutes they watched as the temperature topped out at 101.4 degrees.
Mrs Washington placed her hand on the outside of the cup. “Yep, it’s warm. And wow! That was some dramatic demonstration! The kids will love it!”
“This time,” said Mr. Grow, “evidence of chemical change included both bubbles and heat.”
With Odor Evidence
“Now it’s my turn again,” said Mrs. Washington.
She held a cup near Mr. Grow’s nose. “Give it a sniff,” she said.
“Hey, what’s in there?”
“Just some iron filings. Do you smell anything?”
Mr. Grow shook his head. “No.”
Next, Mrs. Washington held up a small container. “Smell again. This is hydrogen peroxide.”
Again, Mr. Grow shook his head. “No strong odor.”
Finally, Mrs. Washington placed a few drops of the liquid in the cup. Quickly, she held the cup near Mr. Grow’s nose.
“Ewww! Rotten eggs!”
Mrs. Washington grinned. Just what she was looking for. A dramatic way to illustrate that odor is evidence of chemical change.
With Light Evidence
Next, Mrs. Washington took out a container of glow sticks.
“The kids will love those!” said Mr. Grow.
Mrs. Washington nodded and smiled. Then she picked up a glow stick and bent it. Snap! Immediately, it began to glow.
“We can explain that the stick is filled with a liquid. Then, bending breaks tiny capsules full of another liquid. As soon as the two meet, they form a new substance, and light energy is emitted.”
“Perfect!”
Enjoy Teaching Physical and Chemical Change Labs
Both teachers grinned.
“You know, these chemical change labs will be a hit,” said Mr. Grow. “Next, we’ll work on the law of conservation of mass and properties of matter.”
