Engineers Use Catapults to Defeat Lego Trolls!

This week’s Challenge Friday was related to the lever challenge from two weeks ago. We began by reviewing the parts of the lever and how levers are used. Part of our third grade curriculum covers Ancient Greece and Ancient Rome, so next we read about one of the ways that levers were used in Ancient Greece. We read about an Ancient Greek invention – the catapult! We had a conversation about what catapults were used for, how they were made, and what their advantages and disadvantages were. That led to the challenge of the day.


CHALLENGE: Lego knights are being tormented by two trolls! Due to their strength and size, the knights’ swords and spears are powerless against them. They are seeking help from some local engineers to design a stronger weapon to defeat the trolls. Design and build a catapult that will launch a cotton ball “boulder” at the trolls exactly one foot away.


The kids immediately set off to build their catapult. They were given a ruler and recording sheet to measure the distance the cotton ball traveled after each test launch. Many of the children remade their lever from two weeks ago and then modified it to work as a catapult. Some completely changed their lever designs to make their catapults more effective. When they were confident that their catapult would hit a target exactly one foot away, they brought their catapults to me and tried it out against the Lego trolls. The tension was high as they would set up their catapult with the cotton ball “boulder.” Would they defeat the trolls? Some kids got it on the first try! Others missed and went back to make further modifications. Each time they returned, I asked them what changes they had made and why.


The kids were completely engaged and desperately wanted to make their cotton ball hit the trolls! There were several problems when kids were picking partners, however, where one child would whine about another student picking them to be a partner. This coming week, we’ll talk about how to be fair partners and how to be careful with reactions to being picked so that it doesn’t hurt others’ feelings.






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