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[cc highlighting confusing everyday language (different meanings from the chemistry meanings) which is unlikely to change]

Mixing up 'strong' with 'concentrated', and 'weak' with 'dilute' can profoudly alter the meaning in a chemistry context. The meanings of these terms need to be made explicit.

How can this difficulty be addressed?

There are suggestions of activities throughout this topic that support the understanding of 'weak and 'strong': practical activities contrasting differences in reactivity rate, pH and conductivity; the online simulation showing the ions and molecules folloing this page; and a paper activity visualising ionised acids, Explaining acid strength in Developing Understanding.

Can you think of a simple practical activity involving a strong acid, a weak acid, water and a pH meter?

A further practical suggestion is to calculate then measure the pH of 0.1 mol dm^-3 solutions of a strong acid and a weak acid. Then a ten–fold dilution of each solution can be made. It will show that the pH rises by 1 pH unit for the strong acid but, perhaps unexpectedly, only 0.5 of a pH unit for for the weak acid.

This sort of practical activity can also be carried out with a strong alkali and a weak alkali. The ten–fold dilution (and subsequent ten–fold dilution, if desired) will show that pH changes by 1 whole pH unit for every dilution of a strong alkali (or acid) and change by a half pH unit for the weak alkali (or acid).

This topic also includes mathematical expressions. Can you think of something with respect to equations of weak acids that it might be important to stress, in order to limit student misconceptions?

It must be stressed when equations apply to only a weak acid in solution – nothing else. This will avoid the common problem of students using these equations when they don't apply (for example, if some alkali is added).