Students are wrapping up their work with weight, so it’s time for another challenge! Their mission is to create an interesting object weighing exactly 40 grams, using 10 grams each of four different materials: polystyrene (Styrofoam), aluminum foil, plastic modeling clay, and wood.

As they design and construct their objects, students practice measuring, become more familiar with grams, and see that the weight of an object depends both on size and materials. They get hands–on experience with some materials that are heavy for their size and others that are light for their size. They also use what they’ve learned about the additive nature of weight.

By the end of the investigation, students will have revisited many concepts and skills from the unit and will have something interesting to show for it.

Learning Goals

• to measure the weights of different materials and objects in grams
• to use the properties of materials to create an interesting new object
• to understand that the weight of an object is equal to the weights of its parts

Sequence of experiences
1. Pose the challenge	All Class	10 Mins
2. Meet the challenge	Small Groups	25 Mins
3. Make meaning	All Class	10 Mins

Materials and Preparation

For the class:

• 1 tray or seated pan balance

For each group:

• 1 gram weight set
• 2 pan balances
• Styrofoam (more than 10 grams)
• aluminum foil (more than 10 grams)
• plastic modeling clay (more than 10 grams)
• wood stirrers (more than 10 grams)
• scissors
• plastic knives