What a drop of water can tell us

Prepare a shallow tray with a little water, sturdy cups and large sponges. One towel beneath the tray and another within reach help keep the table dry. Present two containers: one holds water and the other is empty. The mission is to move the water with a sponge before trying a cup. Agree that this water is for exploring, not drinking, and stay close throughout the activity. Leave enough working room for a child to squeeze the sponge over the tray without reaching across someone else's hands.

Before wetting the sponge, ask where the water might go. Watch it absorb water and compare a gentle squeeze with a firmer one. Next, transfer the same amount between a wide cup and a narrow cup: the level may change even though no water was added. Pour it back into the original container to check. Keep attention on what actually happened during the transfer. If some spilled, include that loss in the explanation instead of hiding it to produce a predetermined answer about the amount remaining.

Place lleno / full, vacío / empty and gota / drop beside pictures of the containers. Younger children can choose which one to fill and indicate when to stop. Older children can mark a level with tape and record how many transfers with the same cup reach it. Sponges do not always carry equal amounts, so compare attempts and discuss the variation instead of treating each squeeze as an identical measure. Offer a handled cup or help stabilize a container if gripping it distracts from observing the water.

Revisit predictions with a before-and-after drawing: did water pass through the sponge, stay inside or come out when squeezed? Invite children to identify the part of the trial supporting their explanation. If the water remains clean and a plant needs watering, reserve a small amount for that purpose; the whole tray need not go into one pot. Dry the materials and keep two differently shaped containers for another investigation. The next question might be how to move water while leaving fewer drops behind.

Make this idea your own: adapt the materials, pace and support to your group’s ages, interests and needs.