Dinos in Dump Trucks

We began this Force and Motion lesson by reading Sheep in a Jeep by Nancy Shaw.  The children identified examples of force as the sheep's jeep antics unfolded.  When the jeep crashed, resulting in "Jeep in a heap," the "sheep weep."  One of our second year students pointed out that the sheep's tears were pulled down by gravity.  Yes!

I explained to the children that while I wasn't able to find jeeps or sheep, I was able to find both dinos and dump trucks.  This invited a lesson in both rhyme and alliteration. 

Next, we discussed the upcoming lab (always best to do this before children have their hands on materials).  Experienced with experiments and accustomed to critical thinking, the children pointed out, "Some of our dump trucks are bigger than other groups'.  Those bigger dump trucks will roll farther because they have more mass."  They concluded that throughout the experiment, each group would need to use the same dump truck each time.  While the dump trucks I found at Arne's did not have beds that actually dumped, the dump trucks from Walgreens did indeed dump.  Another second-year child worried, "What if the back of our dump truck pops up while it's rolling?  That would change the results."  We decided that if this presented a problem, we use a piece of double-sided tape to prevent the truck bed from hopping up and down.

Finally, each cooperative science group sent their Materials Manager to obtain a dump truck, a ruler, a meter stick, a clipboard, and a stack of books from the supply area.  They used an inverted clipboard and a stack of books to construct a ramp 5 centimeters high.  The dump truck was placed at the top of the ramp, blocked by a ruler, and then allowed to roll down the ramp.  With this simple set-up, the children were able to experiment with a series of variables.

First, the children tested how floor surface affects the distance the truck rolls.  They used meter sticks to measure how far traveled after rolling down the ramp onto the tile floor (3 trials). 

They then compared their results with the distance traveled after rolling down the ramp onto carpet.  Our young scientists observed that with the same amount of force, the dump trucks traveled much farther on the tile floor, due to less friction. 

 

Floor surface	Trial 1 Distance (cm)	Trial 2 Distance (cm)	Trial 3 Distance (cm)	Average Distance (cm)
Tile
Carpet

Our young scientists observed that with the same amount of force, the dump trucks traveled much farther on the smooth tile floor than on the carpet, due to less friction.  The children were then challenged to apply this knowledge.  "If you were designing wheels for a truck to travel on ice, in what way(s) would you change the tires to make them safer on a slippery surface?"  "Is a truck able to travel faster on a smooth road or on grass?  Explain why."

Next, groups investigated how ramp height impacts the distance the dump truck rolls.  First, students constructed a ramp that was 5 centimeters high and allowed the dump truck to roll down the ramp three times, recording the distance the truck traveled each time (and calculating an average). 

The children then compared these results with results gathered when they performed three more trials raised with the ramp raised to 10 centimeters. 

 

	Ramp Height	Trial 1 Distance (cm)	Trial 2 Distance (cm)	Trial 3 Distance (cm)	Average Distance (cm)
Gentle slope	____  cm
Steep slope	____  cm

The children noticed that the trucks traveled much farther when they rolled down a steep ramp.  Why?

Finally, the children were ready to examine the affects of ramp height on the outcome for a dinosaur passenger.  When I explained this section of the lab, one of the children hypothesized, "Uh, oh!  Those dinosaurs are going to become extinct all over again!" 

The children worked together in their groups to construct a ramp that was 5 centimeters high and allowed the dump truck (with its dinosaur passenger) to roll down the ramp into a barrier three times, recording the distance the dinosaur traveled each time (and calculating an average). 

The children compared those results with results gathered when they raised the ramp to 10 centimeters and performed three more trials.  The children noticed that the dinosaur was thrown from the truck when it traveled down a steep ramp.  They applied what they learned to driving safety.  "Is it safe to ride in the back of a pickup truck?  Explain why or why not."  "Tell about a safety invention that helps protect passengers in vehicles.  Explain why it works."  "What could you do to help your dinosaur?" 

There's a Book for That!
Forces Make Things Move by Kimberly Brubaker Bradley
Sheep in a Jeep by Nancy Shaw
Picture-Perfect Science Lessons: Using Children’s Books to Guide Inquiry