A team designs a container to keep a cup of water cold for two hours. The rules say it must cost under $5. One design keeps the water coldest, but its materials cost $12. What should the team do?

A class is designing a bird feeder. It must hold seed for three days, be safe for birds, and be built from materials costing no more than $8. Which part of this design problem is a constraint?

A team is designing a lunch bag that keeps a sandwich cool until lunchtime. After building two bags, what should the team measure to decide whether a design succeeded?

A team compares two paper gliders. They fold the second glider from heavier paper and also throw it much harder than the first. The second glider flies farther. What is wrong with this test?

Two model cars are rolled down a ramp to compare wheels made of rubber with wheels made of plastic. For the comparison to be a fair test, what must be kept the same for both cars?

A class needs a shade cover for the school garden. It must block most of the sunlight and be finished in one class period. Design A blocks the most sun but takes two days. Design B blocks most of the sun in one period. Which is better?

A cardboard boat holds its cargo for a minute, then water begins seeping in at one taped seam and the boat sinks. Which part of the design should the team improve first?

Before building anything, a team sketches three different ideas for a tower that must hold a book. Why is drawing several possible solutions helpful?

Two cup designs were each filled with cold water and checked after two hours, three separate times. A team claims Design B keeps water colder. What best supports that claim?

A model bridge must hold a heavy load and weigh less than 200 grams. Design C holds the most weight but the bridge itself weighs 340 grams. How should the team judge Design C?

A team designs a solar oven that must reach 150 degrees Fahrenheit to melt cheese and must be built using only materials from a recycling bin. Which part of this design problem is a criterion for success?

A team builds two model windmills. They test the first one indoors with a small desk fan and the second one outdoors on a breezy day, then decide the second windmill is the better design. This is a fair comparison.

A team builds two toy parachutes and wants to compare how long each stays in the air. What should they do to make this a fair test?

A class may use only recycled materials from the classroom bin to build a planter. A team's plan calls for new lumber from a store. What does this tell the team?

A team tests a cart ramp and finds it is too steep for the cart to roll up safely. The rest of the design works well. What is the best next step?

Four teams built a water filter and each ran a different test on it. Why can the class not tell which filter cleaned water best?

A kindergarten book bag must hold four picture books and be easy for a small child to carry. Bag A holds four books but is too heavy for a small child when full. Bag B holds four books, and a small child carries it easily. Which bag meets the need?

Before building a full-size trash sorter for the cafeteria, a team builds a small working model out of cardboard and tests it. Why build the model first?

Two teams each test a wind-powered cart on the same track with the same fan setting. What should they record so the two solutions can be compared?

Two playground shades both meet the cost, materials, and two-day time limits. The goal is to block as much sun as possible. Shade A blocks 90 percent of the sunlight and Shade B blocks 60 percent. Which should the class choose?