One of our recent Morning Messages asked which of two containers, one skinny stem vase and one squat bouillon jar, held the most water. The children also had the option of answering that their capacity was equal. The majority of the children guessed that the tall container would hold the most. All but one of the remaining children guessed the smaller, wider jar would hold a greater amount of water. With only one thinking that they might be equal, it was time to experiment.
We asked for suggestions for how we could find out the answer. The first answer obviously tapped previous knowledge. “We could use a ruler!” So we gave it a try. We found out a few interesting things, but we still didn’t know which held more water.
The next idea built off of the first. “Let’s use the measure tape!” The measuring tape was retrieved from the dramatic play area and the outside of both containers was compared. The final decision was that this only told us how “wide the glass” was, not how much water it could hold.
Finally, one voice suggested that we could pour the water from one container into the other to see which held more.
The children were quite surprised to find that they held an equal amount of water.
The ability to discern that a quantity remains the same, despite changes in appearance, is called conservation. This is a concept that children generally do not have a strong understanding of without many supporting experiences. It is also a great playful experiment for bath time. Trying various sizes and shapes of containers and marveling at the outcome supports their learning of this concept as well as bolstering problem solving, hypothesizing, and language.