Plaintiffs-appellees brought this suit originally in the Court of Common Pleas of Allen County, Ohio, to recover for injuries sustained by the minor plaintiff as the result of a railroad crossing accident. On a motion by the defendant-appellant, the case was removed to the United States District Court for the Northern District of Ohio, which entered judgment on a jury verdict for the plaintiffs. Defendant-appellant has appealed that judgment alleging numerous grounds for error. We find no reversible error in the proceedings below, however, and affirm the judgment of the District Court.
The accident occurred in Uniopolis, Ohio, at a two-track grade crossing, consisting of a main track and an elevator sidetrack spaced about eighteen feet apart. The railroad track ran north and south, intersecting with the east-west Highway 67. On the day of the accident, as the result of a crew working at a grain elevator area near the crossing, the crossing signal had been activated for 20-25 minutes prior to the accident. Diane Lones, the minor plaintiff, 15 years 10 months of age, and a friend, Melanie Golden, had been riding their bicycles in the area during the time that the crew was working near the crossing and had passed over the grade crossing against the signal at least one time before the accident. Some of the train crew had seen the children playing at or near the crossing.
Just before the accident Diane and Melanie met Jimmie Evans and the three were playing in an elevator area east of the grade crossing when Diane decided to ride over to the crossing. As she approached the crossing the train crew was in the process of making a “flying switch”: a maneuver by which cars at the end of the train are switched onto the sidetrack with sufficient momentum to permit *117coupling -with other ears on the sidetrack. In this case the train was traveling from south to north. The evidence is in conflict whether the train engines were approaching the crossing, on the crossing, or just past the crossing when Diane rode upon the sidetrack. At this time a cut of three cars south of the crossing was floating freely down the sidetrack as a result of the flying switch maneuver. One crew member was at the rear of the first car of the cut of cars to brake the cut and otherwise to control the coupling of the cut with other cars north of the crossing. This crew member’s view of the track in front of the cut was severely restricted; he could see only a limited amount of the track even by leaning out to the side of the cut.
Evidence is in conflict whether Diane stopped her bike on the sidetrack or between the two tracks. Likewise, evidence is conflicting whether the engineer or other crew-, members saw Diane on the crossing as the train approached the crossing, when the train came onto the crossing, or after the train was on the crossing. In any case, as a result of the noise of the diesel engines in front of her Diane did not hear the cut of cars coming down the sidetrack and became aware of the danger only from the shouted warnings of either her friends, who had also come down near the crossing, or the members of the train crew. In response to the warnings Diane either stepped backward slightly or turned to look over her shoulder, but she saw the danger too late to avoid being struck by the cut of cars.
This brief factual outline will be sufficient to deal with the objections raised by the defendant-appellant; for due to the nature of the objections raised only the evidence' most favorable to the plaintiffs can properly be considered by this court.
In this case, as in any diversity action, in considering each issue raised by the defendant-appellant we must first; answer the threshold question as to what body of law the court must look to ascertain the standard to be applied; in resolving that particular issue. The doctrine of Erie R. Co. v. Tompkins (1938), 304 U. S. 64, 58 S. Ct. 817, 82 L. Ed. 1188, is not all-pervasive; where the doctrine begins usually presents no problem, but where the emanations of *118that doctrine cease to affect the proceedings in a federal trial court is a more perplexing determination. Compare Ragan v. Merchants Transfer & Warehouse Co. (1949), 337 U. S. 530, 69 S. Ct. 1233, 93 L. Ed. 1520, with Hanna v. Plumer (1965), 380 U. S. 460, 85 S. Ct. 1136, 14 L. Ed. 2d 8.
Matters that can clearly be labeled substantive, such as the standard to be applied in determining whether the defendant-appellant was negligent, are of course, controlled by state law. We do not take it, however, that the defendant-appellant seriously contends that under the facts of this case it could not have been found negligent under the law of Ohio. The flasher signals were activated for a period of 20-25 minutes. During that time several crewmen had seen children playing near the crossing, and at least one crewman had seen children passing over the crossing in violation of the flasher signals. In spite of this knowledge, the crew switched a cut of cars onto the sidetrack under the control of a crewman whose view of the track was severely restricted. No special precautions were taken; no flagman protected the crossing; and from their testimony, apparently the crew did not even bother to keep a special lookout for children. The engine blocking the crossing might prevent automobile drivers from coming onto the crossing, but it would have no effect on the danger to children that the crew knew, or should have known, existed at that time. In Ohio the care to be observed in avoiding injury to children is greater than the care required to avoid injuring adults. Cleveland Rolling-Mill Company v. Corrigan (1889), 46 Ohio St. 283, 3 L. R. A. 385; Maumee Valley Railways & Light Co. v. Hanaway (1915), 7 Ohio App. 99.
On the other hand, the defendant- appellant does strongly urge that the issue of the minor plaintiff’s contributory negligence should have been taken from the jury.1 This contention is based on alternative grounds: *119(1) that violation of the flasher signal was negligence as a matter of law, or (2) that under the evidence presented the only conclusion the jury could reach was that the minor plaintiff was negligent. If either ground is correct, it would have been reversible error for the District Court to fail to instruct the issue of contributory negligence out of the case. Moore v. Smith (3rd Cir. 1965), 343 F. 2d 206. We find, however, that the minor plaintiff was not negligent per se under Ohio law and that sufficient evidence was presented under both the federal standard and the Ohio standard to take the issue of contributory negligence to the jury.
Eesolution of the question raised by the first ground is clearly controlled by Ohio law. As indicated earlier, statutes or case law that make specific acts or omissions negligence are regulations of primary activity that are substantive under the Erie doctrine and thus must be followed by the federal courts in diversity actions. See Hanna v. Plumer (1965), 380 U. S. 460, 474, 85 S. Ct. 1136, 14 L. Ed. 2d 8 (Harlan, J., concurring). Section 4511.62 (Page, 1965), Revised Code, provides that no one shall drive a vehicle, which includes a bicycle, over a railroad grade crossing when a clearly visible electric signal is operating. No one contests that the minor plaintiff violated this statute, but in Ohio violation of a statute by a child is not negligence per se. Michaelsky v. Gaertner (1935), 53 Ohio App. 341. Whether the violation is negligence depends upon the mental capacity and experience of the child and upon the circumstances of the particular case. Wheaton v. Conkle (1937), 57 Ohio App. 373.
These cases make it clear that the negligence of a child is always a fact question; therefore, the defendant-appellant’s alternate ground for taking the issue of contributory negligence from the jury must be resolved. Determining whether the evidence in this case was sufficient to go to the jury, however, raises a collateral issue, whether *120the applicable standard is the federal standard or the state standard, on which there is a considerable conflict of opinion in the Circuits.2 Our early cases, O’Donnell v. Geneva Metal Wheel Co. (6th Cir. 1950), 190 F. 2d 59; Lovas v. General Motors Corp. (6th Cir. 1954), 212 F. 2d 805, holding that the state law applied, were decided at a time when the decisions of the United States Supreme Court indicated that for purposes of diversity jurisdiction a federal court was, “in effect, only another court of the state * * *” Guaranty Trust Co. v. York (1954), 326 U. S. 99, 108, 65 S. Ct. 1464, 1469, 89 L. Ed. 2079; Stoner v. New York Life Ins. Co. (1940), 311 U. S. 464, 61 S. Ct. 336, 85 L. Ed. 284. More recent decisions of the Supreme Court indicate that such a broad rule states too much and that “* * * ‘outcome-determination’ analysis was never intended to serve as a talisman.” Hanna v. Plumer (1965), 380 U. S. 460, 466-467, 85 S. Ct. 1136, 1141, 14 L. Ed. 2d 8; Byrd v. Blue Ridge Rural Elec. Co-op (1958), 356 U. S. 525, 78 S. Ct. 893, 2 L. Ed. 2d 953. These recent developments would make a review of our position appropriate, but we will not reach out to decide the issue since it appears that the Ohio standard and the federal standard are the same.3 Dickerson v. Shep*121ard Warner Elevator Co. (6th Cir. 1961), 287 F. 2d 255, 258.
The federal standard, as stated in Lavender v. Kurn4 (1946), 327 U. S. 645, 66 S. Ct. 740, 90 L. Ed. 916, is:
‘ ‘ Whenever facts are in dispute or the evidence is such that fair-minded men may draw different inferences, a measure of speculation and conjecture is required on the part of those whose duty it is to settle the dispute by choosing what seems to them to be the most reasonable inference. Only when there is a complete absence of probative facts to support the conclusion reached does reversible error appear. But where, as here, there is an evi-dentiary basis for the jury’s verdict, the jury is free to discard or disbelieve whatever facts are inconsistent with its conclusion. And the appellate court’s function is exhausted when that evidentiary basis becomes apparent, it being immaterial that the court might draw a contrary inference or feel that another conclusion is more reasonable.” 327 U. S. at 653, 66 S. Ct. at 744.
The Ohio courts phrase the standard in a different manner, stating that the court must construe the evidence and all permissible inferences from the evidence in a light most favorable to the non-moving party and that matters of weight and credibility are not for the court, Cothey v. Jones-Lemley Trucking Co. (1964), 176 Ohio St. 342; but the resulting application of the rule is the same.
*122Considering the evidence on the issue of contributory negligence, and all permissible inferences from the evidence, in a light most favorable to the plaintiffs, we find that reasonable minds could differ on the conclusion to be reached. In a rare case where the evidence shows no unusual situation and no evidence is presented to show the minor plaintiff’s lack of appreciation of the danger confronting him, a directed verdict for the defendant is appropriate. Bailey v. Erie R. Co. (N. D. Ohio 1956), 143 F. Supp. 351. This, however, is not such a case. Here the minor plaintiff was confronted by a sidetrack and a main track, not two main tracks, which are frequently used simultaneously. The cut of cars was not a train in the usual sense of that term, and it had no horn or whistle, nor even the noise of an engine, to warn of its approach to the crossing. The minor plaintiff saw the train on the main track, and from the evidence the jury could infer that, given her knowledge and experience, she could reasonably expect no danger from the sidetrack: she was unfamiliar with the switching maneuver employed by the train crew; she had never seen cars moving on both tracks at the same time; and she had seen cars moving on the side track only when being pushed by an engine.
In Leach v. St. Louis-San Francisco R. Co. (6th Cir. 1931), 48 F. 2d 722, a case decided during the Swift v. Tyson5 era, this court refused to hold a twelve-year-old boy, who jumped aboard a slowly moving train and was injured, guilty of contributory negligence as a matter of law. Also in our decisions applying Ohio law, we have been reluctant to hold even adults guilty of negligence as a matter of law when they are confronted with unusual situations. See New York Central R. Co. v. Delich (6th Cir. 1958), 252 F. 2d 522; Fannin v. Baltimore and O. R. Co. (6th Cir. 1958), 253 F. 2d 173. With this background in the Circuit in applying both federal and state law and under the circumstances of this case, we find that the issue of contributory negligence was properly submitted to the jury under an accurate instruction of the Ohio law.
*123Defendant-appellant further contends, however, that even if the issue of contributory negligence was properly submitted to the jury, it was prejudiced by the District Court’s charge to the jury on the doctrine of last clear chance. The asserted error,is based on two grounds: (1) that the evidence does not prove the necessary elements for application of the doctrine, or (2) that the charge was inadequate. Whether the giving or failure to give certain instructions is reversible error is clearly controlled by Rule 51, Federal Rules of Civil Procedure, Hanna v. Plumer (1965), 380 U. S. 460, 85 S. Ct. 1136, 14 L. Ed. 2d 8, supra; but it is equally clear that since the trial judge must “* * * give such explanation or instruction as may be necessary to enable the jury * * * to render a * * * verdict * * *,” Rule 49(b), Federal Rules of Civil Procedure, when a state-created right is being asserted, the state law must be looked to for the substance of the instructions. Lind v. Aetna Casualty and Surety Co. (5th Cir. 1967), 374 F. 2d 377.
Under Ohio law for the doctrine of last clear chance to apply, it must be shown that the defendant became aware of the plaintiff’s situation in time to avoid the accident by the exercise of ordinary care. Peters v. B. & F. Transfer Co. (1966), 7 Ohio St. 2d 143. Also the evidence must show that the plaintiff’s negligence did not continue and, concurrently with the defendant’s negligence, contribute to the accident. Columbus Green Cabs Inc. v. Seip (1952), Ohio App., 115 N. E. 2d 5; Brock v. Marlatt (1934), 128 Ohio St. 435. It is defendant-appellant’s contention that the timely discovery of the minor plaintiff’s perilous position by the train crew and the cessation of the minor plaintiff’s contributory negligence, if any negligence was found by the jury, cannot properly be inferred from the evidence in this case. If the defendant-appellant is correct, the District Court erroneously submitted the doctrine to the jury, and the defendant-appellant would be entitled to a new trial. McFall v. Tooke (6th Cir. 1962), 308 F. 2d 617, 623.
Application of the last clear chance doctrine becomes necessary only if it is assumed that the jury found the minor contributorily negligent. That the minor plaintiff *124might have been negligent in going onto the crossing does not mean, however, that snch negligence continued as long as she remained on the crossing. Under the evidence, the jury could have found that the minor plaintiff was negligent in riding past the flasher signals but that once she was on the crossing with the train engines in front of her that she had no reason to expect danger from the sidetrack and therefor her original negligence ceased. Further, the jury could have found that remaining on the side track, without taking special precautions, was not negligence considering the minor plaintiff’s age and experience.
In its argument on the “discovered peril” element of the Ohio last clear chance doctrine, the defendant-appellant cites several Ohio cases where there was no evidence to support application of the doctrine. E. g., Farmer v. Pittsburgh, C., C. & St. L. R. Co. (1947), 83 Ohio App. 321; Kubick v. Cleveland R. Co. (1929), 7 Ohio Law Abs. 91. But those cases are of little assistance to us in deciding the instant case where there is evidence to justify application of the doctrine. It must be borne in mind that in determining whether the evidence was sufficient to present a case for the jury our function is exhausted when an evidentiary basis becomes apparent. Lavender v. Kurn (1946), 327 U. S. 645, 647, 66 S. Ct. 740, supra.
Bearing in mind that the jury may discard or disbelieve whatever evidence is inconsistent with its conclusion, we recite that evidence that would show the element of “discovered peril.” The investigating highway patrolman testified that one of the engineers said that he saw the minor plaintiff as the train approached the crossing, and Jimmie Evans testified that as the train approached the crossing he saw one of the engineers wave to the minor plaintiff. It is immaterial that there were some apparent contradictions from prior statements or that the defendant-appellant’s engineers denied seeing the minor plaintiff until the engines were on the crossing. The witnesses’ credibility and the weight to be given their testimony were matters for the jury. Dickerson v. Shepard Warner Elevator Co. (6th Cir. 1961), 287 F. 2d 255, 259. So it is clear *125that the jury could conclude that the train crew discovered the minor plaintiff’s perilous position.
On the question of whether the discovery was in time to avoid the accident by the exercise of reasonable care, the jury could conclude from the evidence concerning the relative speeds and positions of the cut and the engines and the length of time that the minor plaintiff was on the crossing that at the time the engineer discovered the minor plaintiff’s position there was a considerable distance between the cut and the crossing. The engineer was near the whistle, and three short blasts on the whistle would have alerted the crew that some obstruction was on the track. From the testimony of the brakeman in control of the cut of cars the jury could infer that if such a signal had been given he would have looked to the track in front of the cut of cars and would have had time to stop the cars.6 So it is also apparent that there was an evidentiary basis on which the jury could consider the doctrine of last clear chance.
Defendant-appellant’s contention that the instructions to the jury on last clear chance were inadequate is based on the assertion that the court failed to properly instruct on the plaintiff’s continuing negligence. The District Court did charge that the plaintiff’s contributory negligence must cease for the doctrine of last clear chance to apply and, in our view, gave a fair and complete instruction on the applicable law of Ohio. Therefore, the court’s failure to give the defendant-appellant’s requested special instruction was not error. Tyree v. New York Central R. Co. (6th Cir. 1967), 382 F. 2d 524.
The remaining objections concern the admission or exclusion of evidence, the introduction of the issue of wan*126ton misconduct, and certain alleged jury misconduct. Rule 43(a), Federal Rules of Civil Procedure, controls the admission and exclusion of evidence in the federal courts, Erie R. Co. v. Lade (6th Cir. 1954), 209 F. 2d 948, and Rule 61 determines whether any error was reversible error. Clearly, under the broad discretion provided by Rule 15(b), F. R. C. P., to amend the pleadings to conform to the evidence, it was not error to allow the introduction of the issue of wanton misconduct even if that issue was not pleaded. The Ohio cases cited by defendant-appellant are inapposite. We find no error in the District Court’s rulings on these points and consider the issue of jury misconduct to be completely without merit.
Judgment affirmed.
Defendant-appellant presented the issue of the minor plaintiff’s contributory negligence in three different questions: the first question concerned the District Court’s failure to grant a directed verdict, the second the court’s failure to grant a judgment notwithstanding the *119verdict, and the third concerned the court’s failure to charge the jury that the minor plaintiff was guilty of contributory negligence as a matter of law. We consider all three questions as presenting essentially the same argument.
The federal standard is applied in the Fourth, Fifth, Ninth, and Tenth Circuits: Davis Frozen Foods, Inc., v. Norfolk Southern R. Co. (4th Cir. 1953), 204 F. 2d 839; Planters Manufacturing Co. v. Protection Mutual Ins. Co. (5th Cir. 1967), 380 F. 2d 869; Smith v. Buck (9th Cir. 1957), 245 F. 2d 348; Basham V. City Bus Company (10th Cir. 1955), 219 F. 2d 547, 52 A. L. R. 2d 582. The Sixth and Eighth Circuit apply the state standard: Lovas v. General Motors Corp. (6th Cir. 1954), 212 F. 2d 805; Continental Can Co. v. Horton (8th Cir. 1957), 250 F. 2d 637. The positions of the Second and Third Circuits is in some doubt: compare Reynolds v. Pegler (2d Cir. 1955), 223 F. 2d 429, 434; and Woods v. National Life and Accident Ins. Co. (3d Cir. 1965), 347 F. 2d 760; with Presser Royalty Co. v. Chase Manhattan Bank (2d Cir. 1959), 272 F. 2d 838; and McDermott v. John Hancock Mut. Life Ins. Co. (3d Cir. 1958), 255 F. 2d 562. See generally 6 Moore, Federal Practice Par. 50.06 (1967).
Applying the state standard has not been outcome determinative in most of our decisions. In some cases, when we have considered the problem a re-examination of our position was made unnecessary because the state standard and federal standard were the same. Price v. Firestone Tire and Rubber Co. (6th Cir. 1963), 321 F. 2d 725; Gilreath v. Southern R. Co. (6th Cir. 1963), 323 F. 2d 158; Dean v. South*121ern R. Co. (6th Cir. 1964), 327 P. 2d 757. In others the issue was not presented because the question was whether the plaintiff had proved the necessary elements of his case. See e. g. Hall v. Marshall (6th Cir. 1968), 394 F. 2d 790. Compare Safeway Stores v. Fannan (9th Cir. 1962), 308 F. 2d 94, 97. Only in Trivette v. New York Life Ins. Co. (6th Cir. 1960), 283 P. 2d 441, might application of the federal standard have made a difference in the result reached.
Lavender v. Kurn was an F. E. L. A. case, but we have cited F. E. L. A. cases in the past, e. g. Wilkerson v. McCarthy (1949), 336 U. S. 53, 69 S. Ct. 413, 93 L. Ed. 497, as stating the federal rule for sufficiency of the evidence. See Dickerson v. Shepard Warner Elevator Co. (6th Cir. 1961), 287 F. 2d 255. The controversy over whether F. E. L. A. cases state the federal standard for sufficiency of the evidence in common law cases was aptly resolved by the Fifth Circuit in Planters Mfg. Co. v. Protection Mutual Ins. Co. (5th Cir. 1967), 380 P. 2d 869.
41 U. S. (16 Pet.) 1, 10 L. Ed. 865 (1842).
The brakeman testified that he could have stopped the cut in one and a halt car lengths. Defendant-appellant attempted to get into evidence the engineer’s opinion that the cut could not have been stopped. We think that the District Court properly sustained the plaintiffs’ objection to the question. Even if such evidence was admissible, however, the engineer answered the question, and since the answer was before the jury, the District Court’s mere sustaining of the objection would have been harmless error. Rule 61, Federal Rules of Civil Procedure.