Comparing Possible Solutions

Question 1

Jaden is packing a peanut butter‑and‑jelly sandwich for a school field day that will last 3 hours. The weather will be warm (about 28 °C). His snack must stay cool enough not to get soggy, and his lunch container must weigh no more than 300 g and cost no more than 2. Which of the following solutions best meets all of the criteria?

Accepted Answer

A small cooler bag with a frozen gel pack (weighs 280 g, costs 1.80, keeps food cool for about 4 hours).

Answer

A metal lunchbox with a foam insert (weighs 350 g, costs 1.50, keeps food cool for about 2 hours).

Answer

A zip‑top plastic bag (weighs 20 g, costs 0.10, keeps food cool for about 30 minutes).

Answer

A paper bag (weighs 30 g, costs 0.05, provides no cooling).

Question 2

A fourth‑grade class must design a small bridge that can hold at least 5 marbles. The bridge must be light (no more than 130 g) and the design can use no more than 30 items (popsicle sticks, straws, or rubber bands). Which of the following designs best meets all of the criteria?

Accepted Answer

Use 25 popsicle sticks glued together in a triangular truss shape; it holds 6 marbles and weighs 120 g.

Answer

Use 20 rubber bands twisted into a net; it holds 5 marbles and weighs 150 g.

Answer

Use 15 straws taped together in a rectangular frame; it holds 3 marbles and weighs 80 g.

Answer

Use 10 popsicle sticks and 10 straws combined in a flat platform; it holds 5 marbles and weighs 200 g.

Question 3

A fourth‑grade class is planning a field‑trip snack. They need a container to keep a small tub of ice cream cold until lunch (about 2 hours). The container must also be lightweight (no more than 500 g) and must fit inside a backpack that is 30 cm long, 20 cm wide, and 10 cm high. Which of the following container designs best meets all of the criteria?

Accepted Answer

A metal lunchbox that is 25 cm × 15 cm × 8 cm, weighs 450 g, and has a built‑in ice pack that stays cold for 3 hours.

Answer

A foam insulated container that is 27 cm × 16 cm × 9 cm, weighs 520 g, and uses a frozen water bottle that stays cold for 2 hours.

Answer

A cardboard box that is 28 cm × 19 cm × 9 cm, weighs 300 g, and is lined with a thin foil sheet that keeps ice cream cold for about 1 hour.

Answer

A plastic cooler bag that is 35 cm × 18 cm × 9 cm, weighs 400 g, and uses a frozen gel pack that stays cold for 2 hours.

Try three questions

A fourth‑grade class must design a small bridge that can hold at least 5 marbles. The bridge must be light (no more than 130 g) and the design can use no more than 30 items (popsicle sticks, straws, or rubber bands). Which of the following designs best meets all of the criteria?

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