What should I do if my students respond like this....?

When a student was asked to explain the difference beteen a compound and a mixture, this was their response.

'A mixture is a pure, single substance, whereas a compound is two or more substances.

Reflect upon each question before revealing the suggested answers.

What is the problem with this answer?

The main issue here is that the student is confused over the defintions of elements, mixtures and compounds.

What could you do to help the student overcome their misconception?

Revisit the definitions of element, mixture and compounds.

Use molecular models to show the difference

Do the  iron and sulfur experiment or show the accompanying video which clearly shows the difference between elements, mixtures and compounds.

How will you make time to address these issues?

The misconceptions identified here are really important basic concepts, that students must understand if they are to make further progress with chemistry. Investing a bit more time now will certainly pay off further down the line. You could use the AfL iron and sulfur lesson which provides an opportunity for students to:

• reinforce and build upon ideas of elements, mixtures and compounds
• investigate the reaction between two elements to make a compound
• describe a chemical change using the particle model