The Kitchen Lab Weight Check

Three Changes at the Snack Counter

Maya and Luis set up a kitchen science lab to investigate a question: Does the total weight change when food is mixed or changed? They used room-temperature water, sugar, oats, raisins, and crackers. Nothing was heated, and they did not taste the investigation materials. They measured each complete container before and after its contents changed. Their digital scale showed weight in grams.

For the dissolving test, they placed water in a jar. A small, dry cup of sugar stood inside the jar, above the water. They closed the lid and weighed everything together. Then they tipped the closed jar so the sugar fell into the water. They gently swirled it until they could no longer see sugar crystals. The jar, lid, and empty cup together weighed 120 g. The water weighed 180 g, and the sugar weighed 20 g.

For the mixing test, they placed 80 g of oats on one side of a container and 40 g of raisins on the other side. The container and its lid weighed 60 g. After closing the lid, they measured the total weight. Then they gently shook the closed container to mix the foods. For the crushing test, they sealed 50 g of crackers in a 10 g bag. They measured the total before pressing the crackers into crumbs with their hands.

Each test changed the contents in a different way. Sugar dissolved, two foods mixed, and crackers broke into smaller pieces. During these three tests, the students kept every lid or bag closed. They used the same scale on the same level counter. Before each reading, they waited for the displayed number to stop changing. They kept all the food and all the container parts on the scale for both measurements.

The graph shows their starting measurements. Later, they also investigated water left in open and closed containers. Water can change from liquid to water vapor and enter the air. Water vapor is matter, even when it cannot be seen.