Liquid Hourglass

Materials

• 2 identical clear water bottles

• 2 drinking straws

• Drill

• Scissors

• Duct tape

• Vegetable oil (enough to fill a bottle)

• Water (enough to fill a bottle)

• Markers (optional)

• Food coloring (optional)

• Funnel (optional)

• Hot glue gun

Directions

1. Remove the two caps from the plastic bottles and use glue fun to attach the top of the caps. Make sure you get a good seal by pressing them towards each other.

2. Once the glue is dry, add a strip of duct tape around the conjoined caps to ensure a liquid-tight seal

3. Using your marker, mark two dots on one side of the cap. You will be using the dots as reference for drilling holes.

4. Find a drill bit that has the same circumference as the straw's. Using the drill, drill the two holes through the caps. Don't worry about using a drill bit that is a bit bigger than your straw's circumference.

5. Cut out two 2" long straws. Fit one straw 1/3 down through one hole. Fit the second straw on the other side, 1/3 down through the second hole. If the straws don't have a snug fit, use hot glue or super glue to secure them.

6. Take one bottle and fill it up with vegetable oil using a funnel. Fill the bottle nearly to the top, stopping about 1 cm from the rim.

7. Fill the second bottle with water. Make sure to stop at at the edge where the cap closes. If using, add food coloring now.

8. When the glue on the straws is dry, screw one of the caps onto the bottle of oil.

9. Quickly flip over the bottle of oil and screw the other cap onto the bottle of water. Flip your hourglass over again so that the oil is on the bottom, and the water is on top. Watch as the exchange of liquids mimics an hourglass.

adapted from Kiwi Co