You will need access to hot water for this activity.
Decide How to Distribute Hot Water
Each student will need about 1/4 cup of hot water. Hot water from the tap is hot enough -- in other words, water you can touch without it feeling uncomfortably hot. If you don’t have a sink in your classroom, fill a few bottles with hot water and bring them to the classroom. Keep the water hot by putting the bottles in a cooler or wrapping them in a towel.
We recommend having one container of hot water for each group of 4 students. For each group, you may want to appoint responsible students to help you pour water.