Section 2 f) Specification

2.29 understand that metals can be arranged in a reactivity series based on the reactions of the metals and their compounds: potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver and gold

Some metals are more reactive than others, based on their chemical compositions. More reactive metals will displace less reactive metals in a compound, and they react more strongly. From reactions, we can determine the reactivity series (from most to least reactive):

Potassium K
Sodium Na
Lithium Li
Calcium Ca
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Copper Cu
Silver Ag
Gold Au

2.30 describe how reactions with water and dilute acids can be used to deduce the following order of reactivity: potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper

Potassium, sodium, and lithium are alkali metals, therefore their reactivity series is easily determined by reacting them with cold water. Calcium also reacts with water, but less so. Magnesium, zinc, and iron will only react with cold water very slowly, but will react with acids (e.g. hydrochloric acid) with varying degrees of intensities. 
Copper will not react with either an acid or water.
The more vigorous the reaction, the more reactive the metal.

2.31 deduce the position of a metal within the reactivity series using displacement reactions between metals and their oxides, and between metals and their salts in aqueous solutions

To carry out a reaction to determine reactivity series, dissolve a metal oxide or metal salt in water, then add another metal. If there is a reaction, the metal you introduced is more reactive. If there is no reaction, it is less reactive. This can be done multiple times with different metals to determine reactivity series.

2.32 understand oxidation and reduction as the addition and removal of oxygen respectively

OILRIG says Oxidation Is Loss of electrons and Reduction Is Gain of electrons, but it can also be in reference to loss or gain of an oxygen ion, as they are positively charged; they have more protons than electrons. Oxidation is gain of oxygen ions and reduction is loss of oxygen ions. This is easily memorable as 'oxidation' is rooted from the word oxygen.

2.33 understand the terms redox, oxidising agent, reducing agent

Redox means a reaction involving molecules that are reduced and molecules that are oxidised.
An oxidising agent is a less reactive metal in a compound that allows the other metal to be oxidised.
A reducing agent is a more reactive metal that reduces the other metal.

2.34 describe the conditions under which iron rusts

Under conditions where there is moisture and air; it requires both oxygen and water to rust.

2.35 describe how the rusting of iron may be prevented by grease, oil, paint, plastic and galvanising

Grease, oil, paint or plastic creates a layer between the iron and air and water. It repels water and doesn't allow air in.
Galvanising is a technique of coating iron with zinc, a more reactive metal. The air and water react with the zinc instead of the iron, and preventing the iron from coming into contact with the air.

2.36 understand the sacrificial protection of iron in terms of the reactivity series.

Sacrificial protection means a more reactive metal is made to coat a less reactive one, it then reacts with the air and water instead of the iron.