Babies around one 15-16 months usually are not speaking; but they may say some words and actually they understand everything. I try to communicate with babies as adult people and usually they response in the same way. This is activity for babies but I think younger preschoolers will enjoy this activity also.
There are three bottles: two with colored water - red and blue. and plain water. The bottle with red water is warm, the bottle with blue water - friezed, and plain water is in regular temperature. Try to explain children a concept of hot and cold; sure they will response in proper way!