Laboratories measure the volume of breads by rapeseed displacement. I found that rice grains are also suitable. Students can experiment measuring the volume of their loaves. Just fill a suitable hard box with appropriate dimensions for the bread with grain. Weigh the grain needed to fill the box with and without the loaf.
Students can find the volume of the box by measuring the volume or the weight of water it contains.
Since they know the weight of grain needed to fill the volume of the box, they can now easily find the volume of the grains that are displaced by the bread, by weighing the displaced grains. This volume of the displaced grains equals the volume of your loaf. Cereal chemistry laboratories attach much weight to the volume of loaves when they assess their quality. Ask students to describe the characteristics of their favorite bread. Using this description, they can assess the characteristics of a bread they baked in the classroom or from a bakery.