We are learning from Case Studies in Business Ethics by the late Rabbi Dr. Aaron Levine z"l professor of economics at Yeshiva University.
Questions: Can a child tell a lie as a means of ending a scuffle amongst his playmates?
Rabbi Levine repeatedly stresses the importance of moral education for children. We learned earlier that lies that may be permitted to adults to maintain domestic harmony are not permitted to children.
However, relating to the question above, Rabbi Levine quotes from the contemporary book Titen emet liyaakov, by Rabbi Yaakov Yechezkel Fish. Rabbi Fish quotes both R' Shlomo Zalman Aurbach and R' Yosef Shalom Elyashiv in saying that it is permissible in the above mentioned case for a child to lie to end an argument with peers. But teachers should stress that the use of permissible lies is only the second best solution to real world problems.