Best way to mark out a schooling area in a field?

[Foxy girl]

I've got a 1 acre paddock that's bare as anything after no rain for months so I thought I might sacrifice some of it to create a proper schooling area now I'm having lessons again. Obviously I don't mean the whole menage thing as I haven't got the funds, but have any of you done this in your fields and if so, how do you go about marking it out and what sort of size would I need as a minimum? The narrow end of the field already has 3 good boundaries so I'd only really need to mark off the final long side with something (other than eletric fencing).

Any suggestions grafefully received!

 

[tinap]

If you just need it marking (not fencing) I use either lengths of guttering or those cans of spray that workmen use for marking on roads xx

 

[chickeninabun]

I've done this a number of ways.
I've got some dressage letter cones, which I put out in the relevant places (the ones that spike in the ground are best, but were much more expensive than my cones). I paced out a 20x40m area, but you could probably manage with a 15x30m.
I have fenced mine off with electric on 3 sides before (fourth side being a boundary fence), which worked really well, as my cob is very unschooled and it's nice having the fence to help with steering!
Even if you don't fence it off, after riding on it a few times, the track becomes fairly clear to see, although it can get quite hard when there is no rain, as it'll just wear down the bare mud.
I have even being round the track/diagonals/centre line etc with a lawn mower before when the grass was long! It helped to keep straight down the centre line, as you knew exactly where you were supposed to be riding!