An important part of understanding sea-level rise is understanding thermal expansion of water. Thermal expansion accounts for about half of the measured global sea-level rise. Students will build a model using everyday items to demonstrate that water expands when heat energy is added. Materials Per group of 2-3 students: 1 disposable plastic water bottle, with a flip-top lid, if available. Small bottles made with thicker, sturdier plastic are preferred. 1 clear plastic straw Food coloring Ruler