“I don’t understand our science lesson today, Olivia,” Jolena complained, as the two girls walked home from school.
“It was pretty confusing, I thought,” Olivia agreed. “It will make it harder to do well on the test.”
“That’s just what I was thinking,” Jolena replied. “I mean, we can memorize the words, but if a question on the test asks us to use what the words say, I would have a lot of difficulty.”
The two dolls walked on for a bit in silence, each of them thinking about the problem.
Then Jolena stopped suddenly. “You know, Olivia,” she began, “my sister Mandy knows a lot about science. Maybe she can help us both, if you come to my house. I’m pretty sure she will be home.”
“I would love to see where you live,” Olivia said, “and if Mandy can help, it would be wonderful,” she added.
As expected, Mandy was sitting in the living room, knitting. She looked up when the two dolls came in through the front door.
“Mandy!” Jolena exclaimed. “I’m so glad you’re here! This is my friend Olivia,” she said as she introduced the other doll. “Olivia lives around the corner, close to Nico’s house. She’s in my class at school.”
While the two younger dolls climbed up onto the couch, Mandy removed her glasses and put her knitting down. “I’m happy to meet you, Olivia,” she said and shook Olivia's hand.
“I especially wanted to find you, Mandy,” Jolena said. “We’re both having trouble understanding some things in our science lesson, and we have a test tomorrow. I thought maybe you could help.”
“I’m happy to help if I can,” Mandy assured them. “What’s your question?”
Jolena and Olivia looked at each other. Jolena decided that since she already knew Mandy, she should explain.
“The lesson is about mass, weight, volume and density,” she began. “Now, we understand volume and weight. For instance, when you measure something in a cup, that’s volume, like a cup of flour, or a cup of oatmeal, when I’m baking cookies.”
“And when you put something on the scale to weigh it,” Jolena continued, “like, say, pasta, if the recipe gives the amount you need in weight instead of volume.”
Jolena looked at Olivia to give her a chance to talk.
“Yes,” Olivia agreed. “We have no trouble with that, “and density is easy, too. Density is like the difference between solids, liquids and gases. Solids are denser than liquids, because the atoms are closer together. Liquids are denser than gasses, and some gases are denser than other gases.”
“That’s what makes a balloon filled with helium float in the air,” Olivia concluded. “Helium is less dense than the air. That's why you have to tie that kind of balloon to something, so it won't float away.”
The two younger dolls looked at each other and nodded. They understood all that.
“It’s mass we don’t get,” Jolena said finally. “I know it’s how much matter is in something, but how is that not density?”
“It’s also measured the same as weight, so why isn’t mass the same as weight?” Olivia asked.
Mandy thought for a moment, trying to figure out how to explain. “First of all,” she said at last, “You shouldn’t feel discouraged if this is confusing. It’s a very confusing thing, and scientists haven’t made it any easier for us.”
“You see,” Mandy went on, “words are sometimes used differently in science than in everyday life. Mass is how much of something there is, as you said. It has two parts: volume (or size) and density (or how compact it is).”
“When you make bread dough, Jolena, you have a big lump of dough,” Mandy explained. “Maybe it weighs a pound on the scale. It’s pretty dense until you let it rise and the yeast does its work.
If you decide to make two smaller loaves, you cut the dough into two equal pieces, so the mass of each piece of dough is half as much, but the density would be the same for each lump of dough as it was for the whole thing.”
“That's how mass is different from density,” Mandy went on. “Now, for weight. Let’s say an astronaut on the moon decided to make bread there on the moon….”
Jolena and Olivia looked at each other and tried to imagine the astronaut deciding to stop picking up rocks and instead mix dough to make bread on the moon.
“That lump of bread dough that weighed one pound on Earth would weigh much less, but the mass and density would be the same.”
“Why would the dough weigh less?” Olivia wanted to know. Jolena nodded that she wanted to know, too.
“The moon is much smaller than Earth,” Mandy explained. “And because it’s smaller it has less gravity than Earth. Gravity is what keeps us from floating off the earth. The way scientists use the word weight is about how the force of gravity works on something,” Mandy pointed out, “not simply how heavy it is.” Mandy paused to let that sink in.
“As for mass, the way scientists think of mass,” Mandy said then, “is to talk about how easy it is to move something, or to stop something that’s already moving, like a ball rolling. The greater the mass, the more effort it takes to move it and the harder it is to stop it from moving once you get it going. That,” she said, “would be the same on the moon.”
Jolena and Olivia were quiet for a moment or two, as they thought about what Mandy had said.
“I think I’ve got it now,” Olivia exclaimed suddenly!
“Me, too,” agreed Jolena. “All the time it was the scientists who made up the terms who were confused. Now that we know that, the rest is easy. We just have to pretend to be confused the same way scientists are, and we will do well on the test.”
Now that the dolls had that worked out, Olivia realized that Amber, the child she lives with, would be missing her, so she got down from the couch. “I’d better go,” she said as she walked toward the door. Then she turned around, as if she had just thought of something.
“And now that I know things weigh less on the moon,” Olivia said, “I’m going to tell Amber’s mom she doesn’t have to diet to lose weight. All she has to do is go to the moon. Thanks, Mandy! See you tomorrow, Jolena!”
With that, Olivia was out the door and gone.
Mandy: Götz Happy Kidz Katie 2015
Jolena: Götz Happy Kidz Lena în Aspen
Olivia: Götz Happy Kidz Chosen Ayelet
"The Doll's Storybook" is not affiliated with Gotz Dolls USA Inc. or Götz Puppenmanufaktur International GmbH.
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Copyright © 2025 by Peggy Stuart
