The plaintiff, being only 13 years of age at the time of her fall, is presumed to have been incapable of contributory negligence. Hutchens v. Southard, 254 N.C. 428, 119 S.E. 2d 205; Adams v. Board of Education, 248 N.C. 506, 103 S.E. 2d 854. Though this presumption is rebuttable, the burden of rebutting it is upon the defendants. The judgment of nonsuit cannot be sustained upon the ground of contributory negligence by the plaintiff in her undertaking of the “pique turn” upon a dance floor, which appeared to her to be slick and which she was warned was slick, even if we assume that such a floor is not reasonably safe for this movement. Hamilton v. McCash, 257 N.C. 611, 127 S.E. 2d 214; Wilson v. Bright, 255 N.C. 329, 121 S.E. 2d 601; Adams v. Board of Education, supra.
Nevertheless, to withstand a motion for judgment of nonsuit, the evidence, interpreted in the light most favorable to the plaintiff, must be sufficient to support a finding of negligence by the defendants which was a proximate cause of the plaintiff’s injury. The evidence presented by the plaintiff falls short in this respect.
The proprietor of a school operated for profit, like the proprietor of any other business establishment, owes to those whom he invites to enter and use his premises, for purposes connected with his *66business, a duty to use ordinary care to maintain the premises in a condition reasonably safe for the contemplated use and a duty to warn the invitee against dangers, which are known to or should have been discovered by the proprietor and which are not readily apparent to such observation as may reasonably be expected of such an invitee to such an establishment. York v. Murphy, 264 N.C. 453, 141 S.E. 2d 867; Jones v. Pinehurst, Inc., 261 N.C. 575, 135 S.E. 2d 580; Berger v. Cornwell, 260 N.C. 198, 132 S.E. 2d 317; Norris v. Department Store, 259 N.C. 350, 130 S.E. 2d 537; Goldman v. Kossove, 253 N.C. 370, 117 S.E. 2d 35; Sledge v. Wagoner, 248 N.C. 631, 104 S.E. 2d 195; Revis v. Orr, 234 N.C. 158, 66 S.E. 2d 652; Coston v. Hotel, 231 N.C. 546, 57 S.E. 2d 793; 78 C.J.S., Schools, § 10.
The sufficiency of a warning to the invitee of the existence of a condition upon the premises will depend, in part, upon whether the proprietor should know that the invitee, by reason of youth, old age or disability, is incapable of understanding the danger and of taking precautions for his or her own safety under such conditions. See: Brosnan v. Sweetser, 127 Ind. 1, 26 N.E. 555; Brown v. Stevens, 136 Mich. 311, 99 N.W. 12. A warning sufficient to alert an adult professional dancer to the condition of a dance floor may not be sufficient to absolve the proprietor from liability to a 13 year old pupil for a fall thereon.
The plaintiff, a duly enrolled, tuition paying pupil in the defendants’ school, was an invitee of the defendants when upon their premises for the purpose of attending and participating in the activities of a class in which she was so enrolled. See: Goldman v. Kossove, supra; Williams v. McSwain, 248 N.C. 13, 102 S.E. 2d 464; Pafford v. Construction Co., 217 N.C. 730, 9 S.E. 2d 408; 38 Am. Jur., Negligence, § 99; 65 C.J.S., Negligence, § 43(3).
Nevertheless, the defendants were not insurers of the plaintiff’s safety from falling while upon their premises for such purpose. Jones v. Pinehurst, Inc., supra; Norris v. Department Store, supra; Copeland v. Phthisic, 245 N.C. 580, 96 S.E. 2d 697; 63 A.L.R. 2d 587; Revis v. Orr, supra. Even though she fell while engaged in carrying out an assignment given her in the course of her instruction, the defendants are not liable for her injury unless some negligent act or omission by them was the proximate cause of it.
The defendants instructed plaintiff to undertake the series of “pique turns,” but the plaintiff does not contend that this basic dance step, which she had been performing for several years, was, in itself, dangerous for one of her age and dancing experience. Her contention is that it was dangerous to perform it upon this floor in *67the condition it was in on this particular afternoon, which condition the defendants had produced. Thus, she contends the defendants are liable because they did not use reasonable care to have the dance floor in a condition safe for the “pique turns” which they knew the plaintiff would attempt to make thereon.
What constitutes a reasonably safe condition of premises depends, of course, upon the uses which the proprietor invites his business guests to make of them and those which he should anticipate they will make. 65 C.J.S., Negligence, § 45(b). It also depends upon the known or reasonably foreseeable characteristics of the invitees. 38 Am. Jur., Negligence, §§ 38, 40. A condition reasonably safe for invitees upon an ice skating rink is far different from a condition reasonably safe upon the stairway of a rest home for the aged, or in the aisle between the counters and display racks of a store whose proprietor hopes his invitees’ attention will be attracted to the articles there displayed for sale. The rule of law is stated in the same words for all these situations — the proprietor must use the care a reasonable man similarly situated would use to keep his premises in a condition safe for the foreseeable use by his invitee — but the standard varies from one type of establishment to another because different types of businesses and different types of activities involve different risks to the invitee and require different conditions and surroundings for their normal and proper conduct. The proprietor of a business establishment is not required to take precautions for his invitees’ safety such as will make it impracticable for him to operate or such as will destroy the attractiveness of his establishment for those who normally patronize such places. Pierce v. Murnick, 265 N.C. 707, 145 S.E. 2d 11; Aaser v. Charlotte, 265 N.C. 494, 144 S.E. 2d 610; Revis v. Orr, supra. “The measure of his duty in this respect is reasonable or ordinary care, and in determining whether such care has been exercised it is proper to consider the nature of the property, the uses and purposes for which the property in question is primarily intended, and the particular circumstances of the case.” 65 C.J.S., Negligence, § 45(b).
The defendants operate a school for dancing. On this occasion they knew the invitees would be agile young girls, rather well trained and experienced in dancing. The doctrine of res ipsa loquitur does not apply to a fall in the aisle of a store. Copeland v. Phthisic, supra. Neither does it apply to a fall on a dance floor. It is not negligence per se to wax and polish the aisle of a store. Annotation: 63 A.L.R. 2d 591, 630. Neither is it negligence per se to wax and polish a dance floor. In Fishman v. Brooklyn Jewish Center, Inc., 234 App. Div. 319, 255 N.Y.S. 124, the court said:
*68“Defendant’s negligence is claimed to consist in having placed small pieces of wax upon the floor, whereon plaintiff and other guests were to continue to dance. That practice is too well founded to be condemned as negligent. Dance floors are intended to be made slippery, and plaintiff, with knowledge of the conditions, took the chance of slipping.”
“ [N]egligence is not proven by showing that the [dance] floor had been waxed and ‘as a result’ was slippery * * * The placing of wax or similar substance on the floor to make it smooth for dancing has become an established custom, and unless the owner has been negligent in the materials he used or in the manner of applying them, he is not liable to a person who falls thereon because of its slippery condition.”
There is no evidence in this record to indicate that the spot where the plaintiff fell was waxed or polished more than or differently from the rest of the floor. Nothing indicates that there was any smear or concentration of wax or other substance left undistributed at this point on the floor and upon which the plaintiff’s foot rested when she slipped. The record indicates, on the contrary, that six or seven of her classmates executed exactly the same dance step over this area just before she did. None of the fourteen other pupils was called to testify as to the condition of the floor. The cause of the plaintiff’s fall is left in the realm of conjecture.
Moore, J., not sitting.