The decomposition of hydrogen peroxide can be used very effectively to show the effrect of adding a catalyst such as manganese dioxide.

Possible multimedia - short video clip of the decomposition reaction of H₂O₂ and the change in rate of reaction when a MnO₂ is added - base on resource below - also include in the clip that other transition metals can also be used and show the effect of adding  iron oxide or lead oxide.

Cataylsts for decomposition of hydrogen peroxide - http://www.rsc.org/learn-chemistry/resource/res00000831/hydrogen-peroxide-decomposition

Following the clip discuss some of the features of a catalyst eg. can be re-used, transistion metalsand metal/oxides are often good catalysts due to large surface areas erc for adsorption ie. discuss what makes a good catalyst

AfL Activity - might be better placed in additional resources or applying understanding

The use of a catalyst in the decomposition of hydrogen peroxide is set into the context of the sinking of the Kursk submarine, an event that gained international attention in 2000. In this activity, students respond to text and carry out an investigation.

http://www.rsc.org/learn-chemistry/resource/res00000123/afl-how-do-catalysts-affect-reaction-rates