The sole question for decision in this case is whether plaintiffs’ evidence when considered in its most favorable light for the plaintiffs discloses contributory negligence as a matter of law. The trial court answered this question in the affirmative, and we agree.
 As a student participating in pre-season practice for the Stony Point High School basketball team, Roger Dale Clary was an invitee on the property of defendant. See Hood v. Coach Co., 249 N.C. 534, 107 S.E. 2d 154; Pafford v. Construction Co., *639217 N.C. 730, 9 S.E. 2d 408. A landlord owes a duty to an invitee to use reasonable care to keep the premises safe and to warn of hidden dangers, but he is not an insurer of the invitee’s safety. Wrenn v. Convalescent Home, 270 N.C. 447, 154 S.E. 2d 483; Waters v. Harris, 250 N.C. 701, 110 S.E. 2d 283; Hull v. Winn-Dixie Greenville, Inc., 9 N.C. App. 234, 175 S.E. 2d 607. Specifically, he cannot be held liable for injuries to an invitee when the injuries are caused by the invitee’s contributory negligence. Berger v. Cornwell, 260 N.C. 198, 132 S.E. 2d 317; Waldrup v. Carver, 240 N.C. 649, 83 S.E. 2d 663; Blake v. Tea Co., 237 N.C. 730, 75 S.E. 2d 921; Gordon v. Sprott, 231 N.C. 472, 57 S.E. 2d 785.
 These rules apply to a public school or board of education just as they apply to any other landlord, if the board of education has waived the defense of sovereign immunity (as defendant has done in the present case) by purchasing a liability insurance policy, as permitted by G.S. 115-53. Stevens v. Central School Dist. No. 1, 25 App. Div. 2d 871, 270 N.Y.Si 2d 23 (1966), aff'd mem., 21 N.Y. 2d 780, 235 N.E. 2d 448, 288 N.Y.S.2d 475 (1968) (school owes duty of reasonable care to invitee); Juntila v. Everett School Dist. No. 24, 183 Wash. 357, 48 P. 2d 613 (1935) (school is not an insurer of invitee’s safety); Seel v. City of New York, 179 App. Div. 659, 167 N.Y.S. 61 (1917) (school is not liable to invitee who is contributorily negligent).
“Contributory negligence is such an act or omission on the part of the plaintiff amounting to a want of ordinary care concurring and cooperating with some negligent act or omission on the part of the defendant as makes the act or omission of the plaintiff a proximate cause or occasion of the injury complained of.” Adams v. Board of Education, 248 N.C. 506, 511, 103 S.E. 2d 854, 857; accord, 6 Strong, N.C. Index 2d, Negligence, § 13, pp. 33-34.
 In the present case Roger Dale Clary was a senior student at Stony Point High School who had been a member of the school basketball team for three years. He was thoroughly familiar with the gymnasium and the proximity of the glass panels to the basketball court. He knew, or should have known, that glass will .or can break when a heavy body comes violently into contact with it, and that broken glass is dangerous and can cut a person severely. He had run wind sprints upon many other occasions in this gymnasium and knew, or should have known, *640that he could not stop immediately at the end line of the’basketball court when running at top speed.. He 'knew that the glass panel was within three feet of the end line of the basketball court and in plain view. Yet he chose to run directly at the panel at full speed without slowing down until he was within three feet of the glass. Anyone who runs toward a glass wall at full speed and does not slow down until he is only three feet from the wall would be compelled by his momentum to crash into the wall and suffer injury. We hold that Roger Dale Clary failed to exercise ordinary and reasonable care for his own safety’ under the known circumstances then existing and was clearly negligent. There is no other reasonable inference to be drawn from the evidence. Since plaintiffs’ own evidence established his contributory negligence, the directed verdict for the defendant was entirely proper. Lowe v. Futrell, 271 N.C. 550, 157 S.E. 2d 92; Turpin v. Gallimore, 8 N. C. App. 553, 174 S.E. 2d 697, cert. denied, 277 N.C. 117.
Plaintiffs contend that Clary was excused from contributory negligence, if any, because he was acting under the instructions of his basketball coach. The rule with respect to acting in obedience to the orders of a person in authority requires that such orders be disregarded when a reasonable man under similar circumstances would know that his compliance with such orders would result in his injury. Swaney v. Steel Co., 259 N.C. 531, 131 S.E. 2d 601; see Drumwright v. Theatres, Inc., 228 N.C. 325, 45 S.E. 2d 379; Johnson v. R.R., 130 N.C. 488, 41 S.E. 794; Lambeth v. R.R., 66 N.C. 494.
Since we have reached the conclusion that contributory negligence would bar recovery of the plaintiffs, we do not consider the question of negligence of the defendant Board of Education in the construction and operation of the school gymnasium in the manner herein described.
The injuries suffered by Roger Dale Clary are most unfortunate but the evidence clearly supports the directed verdict for the defendant entered by the trial court.
Chief Judge Bbock and Judge Britt concur.