Rocks are tough. Punching or kicking rocks result in broken bones and a cast for several weeks. We use heavy and powerful tools like sledgehammers or jackhammers to break rocks. In contrast, we can easily splash the water without any injury (a different story if it’s a belly flop). Common sense would say that rocks are way harder than water. Yet water breaks rock all the time! How is this possible?

Rocks expand during the day when heated up and contract during the night when they cool. This repetitive contraction and expansion can cause small cracks in rock because not every piece expands or contracts at the same rate. It is in these cracks that water can collect, and over time this is where the breaks happen. As water flows through these cracks, it pulls any loose sediment with it. Also, water is unique because when it freezes, it expands! The force of the expansion of the water can be stronger than the rock. It often pushes the rock apart from the inside out, sometimes cleaving or separating it into pieces.

In this game, your students will be water traveling through the cracks in a rock. They slowly break the rock from the inside out when they flow and freeze. This tag-based Pac-Man-style game is best played in the gym with scooters. Your students will absolutely love it!

Materials: 

·      A large playing area

o   A gym works best because it has lines, making natural paths for the students to follow.

§  If playing indoors in a gym setting, a minimum ratio of one scooter per two students (even if you have enough scooters for 1:1, don’t bring them all out)

§  If playing inside, you will need two blue pool noodles

o   While not ideal, this game can be played outside on the grass

·      As many cones as you can get

o   In a gym

§  Place cones along some of the gym lines in pairs. Make it wide enough so a scooter can fit through.

o   If you play this game outside, add rubber disc dots to show the movement paths the students can follow along with the pairs of cones. The final result should look like a Pac-Man-style maze.

·      If played in a gym

o   Blue scooters, if possible

o   Blue pool noodles

·      If played outside

o   Blue pennies or jerseys

Minimum Number of Students Needed: This game can be played with as few as five students but is more fun with an entire class.

Age: Lower and Upper Elementary