Engineering Design Challenges — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Skyscrapers is tall buildings made of steel and glass.
Corrected: Skyscrapers are tall buildings made of steel and glass.
Plural subjects must take plural verbs to keep subject and verb agreement.
2. Fix the sentence:
A dam hold back water to make electricity and stop floods.
Corrected: A dam holds back water to make electricity and stop floods.
Singular nouns require singular verbs that end with s in the present tense.
3. Fix the sentence:
Prosthetic legs helps people who lost a limb walk again.
Corrected: Prosthetic legs help people who lost a limb walk again.
Plural subjects use the base form of verbs without the singular s ending.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A skyscraper is a very tall building, often built in big cities.
Skyscrapers use steel frames and elevators to reach hundreds of feet up safely.
2. A dam blocks river water and can be used to make clean electricity.
Dams trap water that spins turbines, generating power without burning fuel.
3. A prosthetic limb replaces a missing arm or leg and helps a person move.
Prosthetic limbs use plastic, metal, and motors to restore movement and balance.
4. Engineers design bridges so cars and people can safely cross rivers or canyons.
Bridges spread weight across supports so heavy loads can pass over rivers safely.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Why do engineers design prosthetic limbs?
Sample answer: Engineers design prosthetic limbs to help people who have lost an arm or leg walk, run, or hold things, giving them back independence and confidence.
Prosthetics restore daily abilities so users can work, play sports, and enjoy life.
2. Pick one structure (skyscraper, dam, or bridge) and explain its purpose.
Sample answer: A bridge lets cars and people safely cross a river or valley, so travelers do not have to drive long distances around the gap.
Each large structure solves a specific community need like travel, power, or housing.