Use this chemistry lesson plan for elementary students as part of a unit on chemistry. It can also be done as a fun experiment on its own. It is important to have some text support with this lesson to make sure students understand the material.
Mixtures and Solutions by Carol Ballard or science textbook
Science journal or notebook paper
Chocolate syrup (optional)
Place students into groups of four or five. Give each group a cup of salad mix and a cup of lemonade. Ask students to separate the salad mix and the lemonade into its original ingredients.
Discuss students’ findings. Talk about how the salad could be easily separated and the lemonade could not. Talk about how a mixture can be easily separated and a solution cannot be easily separated because one substance has dissolved into another. Have students copy salt/water, sand/water, sugar/water, and pepper/water into their journals or on notebook paper leaving space between each phrase. Allow students to discuss in their groups if they think each pair is a mixture or solution. Have each student write a prediction beside the combination.
Pass out four cups of water to each group. They will also need a small amount of salt, sugar, sand, and pepper. Give each group a couple of plastic spoons. Have scientific tools available, such as strainers. This lesson will work best if the strainers have very small holes that can retain sand and pepper.
Have students combine the salt and water. Ask them to write observations as they stir the two together. Then, tell them to separate the two. Allow them to use whatever scientific tools you have available. Remind them if they cannot separate it easily that it is a solution. Have them repeat the same process of combining the water with the sand, sugar, and pepper. When they have finished, debrief about the experiment. Talk about what students discovered. See if students can come up with other examples of mixtures and solutions.
Read about mixtures and solutions using your science textbook or from Mixtures and Solutions. Define mixture and solution. Talk about the important parts of each, like a mixture has two or more materials with different properties. A solution, on the other hand, is a type of mixture that is formed when one material dissolves into another.
At the back of your classroom or the science lab, set up an assessment station. Have a mixture of sand and gravel and a solution of chocolate syrup and milk available. Also, have strainers and spoons available. Have students try to separate them and identify which one is a mixture and which one is a solution. You can also just have pictures of each and have students tell you which one is a mixture and which one is a solution.
Separate solutions. Brainstorm ways to separate solutions of salt water and sugar water. Ideas include adding heat or letting the water evaporate.