###### Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about balancing equations and conservation of mass (GCSE and Key Stage 3)

*This video is an excellent introduction to the importance of stoichiometry when reacting substances. A sufficient BANG is only produced when one part oxygen is mixed with two parts hydrogen. Students must have a good understanding of why we need to balance chemical equations before we introduce coefficients and mole ratios.*

#### Conservation of mass

Key Stage 3 activity on conservation of mass Students use a formative multiple choice question to explore their thinking of conservation of mass following a demonstration. Students then consider why some reactions appear not to support the law of conservation. (PDF)

#### Chemical formula – what does it mean?

Key Stage 3 worksheet on chemical formula. This activity is to check that students understand what a chemical formula means. Do they know the difference between Cl, 2Cl and Cl2? So often students get to age 16 and don’t understand the language of chemistry which makes learning more rewarding concepts much harder. (PDF)

#### Why do we need to balance equations?

GCSE activity on conservation of mass using the hydrogen balloon demonstration. Students think about why chemists balance equations. The activity uses the combustion of hydrogen as an example and links to the video above. Combustion of hydrogen gas is an engaging demonstration that will provide the ‘hook’ to introduce the more abstract concept of balancing equations. (PDF)

#### How to balance chemical equations

GCSE and Key Stage 3 activity on how to balance chemical equations. Students balance simple equations involving concrete examples, such as wheels and cars, by adding coefficients before the object. This activity helps make the jump to more abstract chemical equations easier. Try it before you balance chemical equations – it will hopefully help students understand why we need to balance equations in the first place. (PDF)