The underlying science concept that students must understand before learning how to balance equations, is the Law of Conservation of Matter. Discuss with students several examples of how matter is neither created nor destroyed, no matter which chemical processes it undergoes.
More practically, students must be familiar with the concept of a least common multiple (LCM) before they will be able to effectively balance equations. Make sure that students can find the LCM of several simple numbers, such as 3 and 5, or 2 and 6.
Making It Concrete With Discovery Learning
Instead of teaching students the concept of chemical equations directly, let them figure it out themselves.
- Divide the class into groups, and give each group a chemical equation to work with.
- Have them represent the chemical equation by tearing up colored pieces of paper to make the elements that compose the equation. For example, they might use blue scraps to represent oxygen and pink scraps to represent hydrogen.
- After they finish, have each group discuss how their visual representation seems to contradict the Law of the Conservation of Matter.
- Then encourage them to figure out how to incorporate matter conservation into their visual representation, leading them to understanding the need to balance equations.
- They will need to create additional scraps of material in order to create a representation that takes matter conservation into account.
Translating it to Equations
Once students have understood the concept of balancing chemical equations on their own, they will be more easily able to balance equations. Give each group of students another equation, and have the group figure out how to balance it without using the manipulatives from the previous section. You may want to suggest that they use charts to keep track of elements. Instructions on using these charts are included in the linked article on balancing equations activities.
These balancing equations lesson plans will help you teach this difficult concept in an engaging way. Make sure that each student in your groups understand this concept before moving on.