Grade 4: Water and Salinity

In Fourth Grade, we explored properties of water. Our first activity was an engineering design challenge where students worked in groups creating water filtration systems to clean contaminated waters. We experimented with both physical and chemical changes that are needed to purify water. We, then, used a problem based learning model to help create a new home for animals rescued from oil spills. We learned how different creatures are used to different levels of salinity depending on if they live in a bay or estuary or the ocean. We experimented with water salinity by using hydrometers to measure the amount of gravity in salt water and how it changes and more salt is dissolved. For our next project, we tried to figure out why salt is used to melt ice. We observed what happens when salt is poured on ice cubes and looked at molecules of salt and ice. As a culminating activity, we made ice cream and observed how salt lowers the freezing point of ice, which helps the ice cream making process.