The Lighthouse Workroom Weight Trail

A Weight Check by the Rocky Coast

At a lighthouse on a rocky coast, a science club studies whether matter changes its total weight when its shape changes or when materials are mixed. The club uses a digital scale that measures in grams. For each test, students record every part of the setup before the change. They keep the setup closed when they need to track all of the matter.

First, Eliana places a thin sheet of foil in a sealed plastic bag and records its weight. She presses the foil into a tight ball without opening the bag. Next, Rowan puts dry sand and small shell pieces into a jar with a lid. He records the whole jar before gently rolling it so the materials mix. Last, Priya places water and salt in a capped bottle. She records the bottle before shaking it until the salt is no longer visible. The bottle stays capped during the test.

The students measure the same complete setup after each change. The foil looks different after pressing. The sand and shell pieces are spread through one mixture. The salt is no longer visible in the water. These observations show changes in appearance, so the club compares the scale readings to find out what happened to the total weight.