Deepika was sitting with a bunch of poster colours, a mug filled with water and some brushes, preparing for a drawing competition. Just then her Mom called her for dinner and in a hurry she tripped over the mug and spilled it all over the floor. She hurried to get a mop fearing her mom would yell at her.
At the dinner table her Mom asked her if she had prepared for the test next day. Deepika nodded absent-mindedly, actually feeling more excited about the drawing competition that was to follow the test.
After dinner Deepika sat with her Mom to revise for the test. Her Mom had a quick glance and was quite convinced that Deepika would be thorough with her concepts, as she had enjoyed learning about the water cycle a few weeks back.
She thought a little and asked, “Deepika, what do you think happened to the water you spilled today?” Deepika got a little tense and quietly replied, “It has dried up, Mom!” So her Mom asked, “Okay, so do you think drying is the same as evaporation?” Deepika was getting really restless but answered, “No, Mom… the sun needs to be there for evaporation to happen… Drying can happen anywhere.”
Her mom was startled by the answer. She could not imagine that Deepika had been having a wrong notion about evaporation all this while.
Interestingly, many students, we spoke to, thought on the same lines as Deepika. A look at the table confirms the sad fact concerning this misconception.
Around 5000 students answered this question and 39% of those thought that only water changing to water vapour from the oceans and rivers is an example of evaporation. We conducted student interviews to further investigate these misconceptions.
Some of the common misconceptions were – ‘Evaporation is a process that happens only in the presence of sunlight.’ Some students also thought that evaporation happens only outdoors while drying can happen anywhere.
There are various concepts like evaporation that children learn but are unable to relate to their day-to-day experiences. A higher order concept like 'evaporation' is very well communicated as a phase change process but is explained only with reference to the water cycle.
It is important to realise that concepts could be well internalised if seen in the light of several meaningful and practical situations. Drying and evaporation are the same. So what really happens when water evaporates?
Water turns into a gaseous state when the molecules acquire a certain amount of energy, sufficient enough to overcome the intermolecular forces. Molecules of water, while moving randomly, collide and in the process, impart energy to other molecules. If the energy of a molecule on the surface is enough to change its physical state it will escape from the surface. This is evaporation.
Students constantly build their own models of various processes based on the simplest logic that convinces them. These models may be scientifically incorrect. And hence it's important to correct them. On the other hand, it's not very easy to break their incorrect models unless the illustration given generates a strong conflict with their reasoning. Real life illustrations can help catalyse this process and channelise it in the right direction.
EI is an Ahmedabad based organisation working at the forefront of a driving change in education through research, large-scale assessment and the development of new learning technologies.
