with whom RICHARD S. ARNOLD, Chief Judge, ROSS, Senior Circuit Judge, McMILLIAN, FAGG, MAGILL, HANSEN and MORRIS SHEPPARD ARNOLD, Circuit Judges, join.
A panel of this court affirmed a judgment in favor of Robert L. Lee against the Rapid City Area School District No. 51-4 on a claim that Lee was constructively discharged from his job as a teacher because of his age. Lee v. Rapid City Area School District No. 51-4, No. 90-5499 (8th Cir. Feb. 3, 1992). We reversed in part on the issue of liquidated damages, remanding to the district court. We granted rehearing en banc, vacated the panel opinion, and heard arguments. We now affirm the judgment in favor of Lee and again remand to the district court for entry of an award of liquidated damages consistent with our panel opinion.
After our panel opinion, the School District filed a petition for rehearing and a suggestion for rehearing en banc raising essentially three arguments: (1) Lee waived, abandoned, or became estopped from asserting his age discrimination claims by failing to pursue administrative review before the school board under South Dakota law; (2) the district court erred in excluding testimony of Principal Storm and Assistant Principal Voight about complaints they received concerning Lee’s classroom performance during the 1986-87 school year; and (3) the district court misunderstood South Dakota’s continuing contract law for public school teachers.
We adopt the panel’s recitation of facts, as well as part I of the panel’s opinion, rejecting the School District’s claim that it was entitled to judgment notwithstanding the verdict because Lee failed to pursue his administrative remedies and signed an agreement to retire. We further adopt parts III, IV, and V, holding that the district court did not err in instructing the jury; in refusing to grant a mistrial in response to arguments of counsel; or in denying the School District’s motion for a new trial on the ground that the verdict was against the weight of the evidence. The panel opinion, which has not heretofore been published, is appended to this opinion.
Similarly, although we appreciate that the issue of liquidated damages is a difficult one, we adopt part VI of the *320panel opinion and remand to the district court to award full liquidated damages, taking into consideration the School District’s arguments for offset by the amounts of front pay awarded and the settlement payment. The panel properly held that the district court should consider such issues in the first instance.
In a supplemental brief on rehearing, the School District made additional arguments based on the state law issue, which we find it unnecessary to discuss.
The troublesome issue before us is the exclusion of testimony by Principal Storm and Assistant Principal Voight about the substance of complaints they had received from students and parents about Lee. The court admitted evidence that the administrators had received such complaints, but refused to allow testimony about the substance of the complaints unless they had been documented. Of course, we review the district court’s ruling only for abuse of discretion. Maddox v. Patterson, 905 F.2d 1178, 1179 (8th Cir.1990).
Storm testified in general terms that he had received complaints from parents and students about Lee:
Q: Did you have some complaints from parents and students about Mr. Lee?
A: Correct.
The court later sustained an objection to the question: “Did you hear reports of how Mr. Lee was perceived?” but Storm was permitted to say: “The overall tone of some students was negative.” The School District made no offer of proof at the time of this testimony. Later, the School District’s counsel asked Storm:
Q. Had you had both students and parents express the concern [that Mr. Lee lacks a real concern for his students]?
There was a hearsay objection and the court inquired:
The Court: Did you reduce any of those objections to writing?
A. Mrs. Wood put hers in writing to us, I believe.
The Court: She is the only one?
A. At this time that I have, yes, correct. The Court: Well let me ask this question: you say parents and teachers—or parents and students. You mean some; you don’t mean all of them?
A. No.
Thus, the court itself summarized Storm’s testimony before the jury as saying that some parents and students had expressed concern about Lee. After some further discussion, counsel for the School District withdrew the question.
Storm was allowed to describe Mrs. Wood’s complaint, which was reduced to writing. She came to see Storm after seeing Lee, and stated that Lee was rude and abrupt. She was very upset about it. Storm attempted to contact Lee, but could not because Lee had left fifteen minutes earlier than he was supposed to leave that day.
The School District made its offer of proof at a recess:
[W]e do offer to prove through Mr. Storm, if permitted to do so by the Court, that he received innumerable complaints from, first of all, parents at the beginning of the school year asking that their children not be placed in Mr. Lee’s class because of his reputation which was rampant throughout the community that attended West Junior High School. He would also receive complaints from both students and parents concerning Mr. Lee’s teaching of various sorts, which he can relate in detail....
The court denied the offer of proof, stating:
Now, I could not trust the witness after hearing him for several hours; I could not trust him to recount generally that he had certain objections and based on that he did so and so or he heard so and so....
Your questions] may have been innocent, but your answers that you were getting from that witness were not innocent. It was like opening a flood gate, and I am not going to let that happen .... He was coming to conclusions, and I could not stop him throughout the course of his testimony. It was difficult *321to stop him. For that reason, I am not going to let it in.
The district judge also ruled that the offered testimony was hearsay that did not come within any of the exceptions. The district court pointed to the School District’s Negotiated Agreement with its teachers, which required the district to reduce to writing any complaints about teachers that would be used in evaluating the teacher.1
We first turn to the offer of proof, as error may not be predicated upon a ruling excluding evidence unless a substantial right of the party is affected and “the substance of the evidence was made known to the court by offer” or was apparent from the context of the questions. Fed. R.Evid. 103(a)(2); Strong v. Mercantile Trust Co., 816 F.2d 429, 431 (8th Cir.1987), cert. denied, 484 U.S. 1030, 108 S.Ct. 759, 98 L.Ed.2d 771 (1988). On several occasions the court had expressed concern with the generality of the testimony and the impossibility of cross-examination, yet the offer made no effort to satisfy these concerns. The offer referred only generally to complaints without naming the individuals making the complaints or the specific substance of the complaints they made. Strong emphasized “the importance of expressing precisely the substance of the excluded evidence” in an offer of proof. Id. at 432. The offer simply does not identify specific testimony that the court erred in excluding.
With respect to the substance of the testimony covered in the offer of proof, the offer stated almost nothing that was not already before the jury. The jury had heard repeatedly that parents and students had complained about Lee. The only additional bit of evidence stated in the offer was that parents had asked that their children not be assigned to Lee’s class. Thus, for the most part the offer of proof outlined evidence that was cumulative, and we cannot conclude that the district court erred in excluding such testimony. The situation is not unlike that in Strong, in which the offer of proof proffered testimony that “would add nothing to what had been admitted.” Strong, 816 F.2d at 432.
Additionally, the exchange between the court and counsel shows that the court acted to control a witness it deemed unruly. Federal Rule of Evidence 611 authorizes the judge to exercise reasonable control over the mode of interrogating witnesses. See O’Dell v. Hercules, Inc., 904 F.2d 1194, 1203 (8th Cir.1990). Storm repeatedly volunteered non-responsive statements, which either resulted in objections or interruptions, sua sponte interruption by the court, or a lengthy answer stricken as not responsive. On at least two occasions the court commented on the generality of the testimony and the impossibility of cross-examination. On one occasion the court sua sponte instructed Storm that he could not talk about common knowledge around the school, and shortly thereafter sustained an objection to testimony that the children would have already heard horror stories about going to Lee’s class.
The district court also excluded Assistant Principal Voight’s testimony that parents and students had complained that Lee refused to keep them apprised of their grades. The. court ruled that Yoight’s testimony was hearsay. The testimony again was cumulative, and the School District in its brief admits as much, arguing that the corroborative nature makes it admissible.2
*322The district judge did not abuse his discretion in refusing to allow the testimony proffered in the offer of proof.
Even if we decided that the court acted incorrectly in excluding the proffered testimony, Federal Rule of Evidence 103(a) states: “Error may not be predicated upon a ruling which admits or excludes evidence unless a substantial right of the party is affected.” We are not persuaded that the district court’s rulings were inconsistent with substantial justice. Strong, 816 F.2d at 432.
We affirm the judgment of the district court except that we remand for the award of liquidated damages in accordance with this opinion.
. Although the requirement of the Negotiated Agreement was only one of several grounds for the district court’s ruling, the School District argues that the court's ruling permits a private agreement to alter the law of evidence. This argument misses the point. The terms of the Negotiated Agreement cannot change the hearsay rules, but in limiting what administrators are permitted to consider in evaluating teachers, the Agreement affects the relevance of certain kinds of evidence.
. We have in numerous cases admitted complaints received about an employee and have held them to be determinative. In Halsell v. Kimberly-Clark Corp., 683 F.2d 285, 291 (8th Cir.1982), cert. denied, 459 U.S. 1205, 103 S.Ct. 1194, 75 L.Ed.2d 438 (1983), although no question was raised as to admissibility of the evidence, we considered complaint testimony of a far more specific nature. Cox v. Miller County R-I School Dist., 951 F.2d 927, 930-32 (8th Cir.1991), is a similar decision, with a written record being kept of such complaints, and with *322testimony from complaining parents being received in evidence. The evidence in both these cases was far different from the extremely general information which the offer of proof in this case sought to introduce, and as the district court observed, cross-examination or testing of such evidence would have been impossible. In Estes v. Dick Smith Ford, Inc., 856 F.2d 1097 (8th Cir.1988), we held it error to refuse information going to motive, but we cited a Seventh Circuit opinion stating that a paper trail is seldom made of motives giving rise to a discrimination claim. Id. at 1103. In this case School District regulations required just such a paper trail if the district were to use the complaints to evaluate a teacher. Our earlier cases do not dictate a different result than that which we reach today.