For TeachersEngineering Design in Oregon Science ClassroomsPage 1 of 3
Toad’s New Car Read Aloud–Think Aloud
This document contains the text of the Toad’s New CarReading Handout. Lesson vocabulary is bold. Centered, italicized text like this represents prompts for the teacher to stop the reading and have class discussion.
“Oh dear” muttered Ratty as he scrambled down the trail to Badger’s house. “Oh dear. Oh dear. Oh dear. What is to be done about Toad?” As he said his friend’s name a new wave of anxiety flushed over Ratty, and he quickened his pace. “Oh Toad. He just can’t control himself around motorcars.”
Ask students if they like cars too. Is there someone whose driving they find scary?
Ratty had a right to be nervous, for his good friend had indeed made a mess of things once again, and who knew what Badger was going to do? Badger had unsuccessfully tried on several occasions to get Toad to see the error of his ways and give up driving, but Toad could not help himself. His outings always ended with a crash and his arrest. Toad was addicted to the speed and glory of driving, and so, although he knew cars were bad for him, he still got behind the wheel—lied, stole and cheated to get behind the wheel—whenever the opportunity presented itself. “Oh Badger is going to be so mad”, Ratty thought to himself. “Let’s just hope Mole is able to contain him until I arrive.”
As it turned out Mole was there, having a nice spot of tea, when Ratty arrived harried and panting, at Badger’s burrow door.
“Ah, there you are.” Badger remarked opening the door right as Ratty was about to knock. “Took you long enough to get here, but no matter. Now we are all here, and I have excellent news.”
Ratty thought perhaps the wind was up to its tricks again and making him hear things that hadn’t been said. Badger in a good mood? Impossible! Then again, the moon was full and indeed Badger was in the best of moods.
“Toad and I have finally reached an agreement over his driving,” Badger announced. “We’ve decided to compromise. Instead of a motorcar, he will only drive a coaster car. He will coast down the hill and through Toad Manor’s grounds.”
Ask students if they have heard of coaster cars, or whether they can guess. Discuss until they understand that a coaster car has no engine.
Ratty stared at Badger. How would a car work without anengine? It was clear he didn’t see how a coaster car would solve Toad’s driving problems.
Badger gave an impatient sigh. “Do you know about gravity, Ratty? And force? And friction? Do you know about these things Ratty?”
“I do,” Mole set his teacup down. “But I have never heard of a coaster car. I’m excited to find out what it is though. It must be wonderful if it is something you and Toad can both agree upon.”
“It is wonderful, quite wonderful, but first we had better get Ratty caught up on physics. Would you mind, Mole? It’s been quite a long day and I am not sure I have the patience for educating right now.” Badger settled into his chair and took a long sip of tea.
Ask students if they know what gravity, force, and friction are, or whether they can guess. Write these on a board or overhead.
“Of course, of course,” said Mole and he turned to Ratty. “Don’t let Badger scare you. You already know lots about physics because you experience it every day. You just don’t know the vocabulary yet. Let’s start with forces since both gravity and friction are a type of force, and anyway forces are very simple because they are either a push or a pull.”
“A force is a push or a pull.” Ratty let the words sink in.
Ask students if this is different from the idea of “force” they came up with a minute ago.Then, ask students to come up with other examples of forces.
“That’s exactly it,” Mole nodded. He offered Ratty a biscuit. “A force is nothing else. Think about it Ratty. Every movement made is either a push or a pull. When you walk you push against the ground. When you swim you push against the water. When you open your door, you pull it towards you. And when you trip and fall, the Earth pulls you towards its center. That’s the force of gravity.”
“Gravity is the force that pulls you towards the Earth’s center.” Ratty was pleased. He already knew this scientific fact.
Ask students if this is different from the idea of “gravity” they came up with earlier.
Ask students when they experience gravity. Who does not experience gravity? (ex. Astronauts in space).
Then, ask what happens to a ball at the top of a hill. Discuss until students understand that gravity is what drives a coaster car.
“Exactly right again Ratty,” Mole encouraged. “That leaves friction. Friction is the force of objects pushing and rubbing against each other, which would stop a coaster car.”
“Oh dear,” squirmed Ratty. “Friction makes no sense at all!”
“Let me explain it another way. Rub your hands together. The push of one hand against the other creates friction, which you can feel as warmth. Anytime one object pushes against another object, friction is created.” Ratty and Mole both rubbed their hands together and smiled as they felt the warmth of friction being created.
Ask students if this is different from the idea of “friction” they came up with earlier.
Explain that slippery objects have less friction, and sticky objects have more friction. Ask students for examples of slippery and sticky objects.
Then, ask students what a sticky object with high friction might do to a coaster car (slow down motion).
“Yes, yes, yes,” Badger interrupted. He was anxious to move the instruction along. “Now, about Toad’s coaster car. You see, a coaster car moves by gravity and stops by friction.” Badger saw that both Mole and Ratty seemed to be following the discussion.
“Couldn’t have said it better myself!” Badger beamed. “Now explain what the friction will do.”
It was Ratty that pressed on. “When the car gets to the bottom of the hill, it will continue moving for some distance because the gravity has given it momentum, which is what keeps objects moving once they’ve gotten started. It is friction that will eventually stop it.”
Mole, Badger, and Ratty were all silent for a moment, each envisioning the problems of Toad in a coaster car that wouldn’t stop at the right time. That worry also made them think of other problems, like the car accidentally curving and crashing into a tree or light post.
“I think he’ll be okay.” Badger broke the silence. “Just like with a regular car, you can change the parts of a coaster car to make it travel more quickly or slowly and make it stop more quickly.” He poured tea for both of his guests. They enthusiastically sat and discussed ways they might change the parts of the coaster car to control its movements and became very excited to begin construction.
Ask students what problem the characters are trying to solve (making a coaster car that stops at the right time, and goes straight).
Ask students if they know what an engineer is, or if they can guess. Discuss until students understand that engineers solve problems. Ask if what Toad, Badger, Mole and Ratty are doing could be called engineering.
Explain to students that engineers use something called the engineering design process to solve problems like these.
Ask students to identify the problem(s) in this story. Write these on a board or overhead.
Ask students if they know what a solution is. Discuss until students understand that solutions are inventions that fix the problem.
Explain to students that solutions must meet the criteria, which are what engineers decide must be in the solution. Ask students to identify criteria for this problem. Write these on a board or overhead.
Ask students to discuss what the solution to these problems might look like. Write this on a board or overhead.