Straw Holds Water With a Finger

Water stays inside until finger is removed. Ask students to predict what will happen. Dip straw, cover top with finger, lift it. Key idea: Air cannot enter from above, so pressure supports the water column. Ask: What is holding the water up? Safety and cleanup: Individual demo straw; no mouth use. https://www.google.com/search?q=%22Straw+Holds+Water+With+a+Finger%22+science+demonstration+experiment