Planed - planned

A common careless error - which simple spell-checkers cannot detect - is to type the wrong numbers of '-n-'s in these words. Be clear. (The same applies to planning and planing, and other derivatives.)

• Planed is the past tense and past participle of the verb 'to plane'. A plane is a tool that carpenters use. It is a hand-tool used to make a wood surface flat and smooth. It shaves thin curls of wood off the piece of wood on which it is being used. There is a verb from this tool, 'to plane': "the carpenter planed the table edge until it was smooth."
  • (The word 'plane' in modern times is more usually used as an abbreviation for 'aeroplane' [US: airplane]. This derives from its meaning in geometry, of 'a flat surface'. It is a mistake, in academic English, to use plane as a verb in the sense of 'to fly', or 'to travel by aeroplane'.)
  • Boats can plane when they skim over the 'plane surface' of water by raising the hull, by hydrodynamic lift, out of its normal position floating in the water. Hydroplanes are control mechanisms to adjust the position of a vessel in the water. Aquaplaning is the phenomenon when the wheels of a road vehicle 'ride' on a thin film of water, and so lose contact with the road - hence much of their controllability.

Like the tool, and like the verb, both the flying machine and the flat surface are pronounced to rhyme with 'main', 'lane', 'pain' and 'rain' (IPA: /pleɪn/).

• Planned on the other hand is the past tense and past participle of the verb 'to plan'. This is pronounced to rhyme with 'man', 'can' and 'pan' (IPA: /plæn/, and planned rhymes with 'canned' and 'and' (/plænd/). It means 'an outline of intentions', or 'the way proposed to do something'. Good students should plan their essays. No one ever planes an essay.

So, when you have finished, you have planned an essay with two '-n-'s. You have not planed it, with half the number of '-n-'s.

The same applies to the two nouns planning, which is what good students should do, and planing, which I have never seen the best student try.

You may also like to see an article on another common error, involving a homophone, at plain and plane.