Rooftop Garden Pouch Journal

Notes from Juniper's rooftop garden

Juniper helps care for a vegetable garden on the roof of a city building. She wants to make models of three kinds of matter found in the garden area: air, water, and dry potting soil. An adult helps her use three matching, sealable pouches. Pouch A is filled with air and sealed. Pouch B holds 100 milliliters of water and is sealed. Pouch C holds 100 grams of dry potting soil and is sealed. The pouches do not leak.

On Day 1, Juniper measures each pouch on the same balance. She also records the pouch's outside shape. On Day 2, she gently presses Pouch A while it remains sealed. She records its shape before and after pressing and measures its mass again. On Day 3, she tilts the water pouch and the soil pouch one at a time. She records how the contents are arranged. She does not open any pouch.

Juniper cannot see separate particles of the air, water, or soil inside the pouches. For a model, she uses small dots as symbols. The dots are not drawn at their real size. A key explains that each dot stands for many particles too small to see.