Football sideline assisstance

[anonymous-user]

Hi, just watched Man city v Leicester city and during the match the Leicester management handed a player a piece of paper with a tactical change, how can this be legal? I get the manager shouts from their sideline box during the match but giving instructions seems to be stretching it a little too far. . . if legal why not give the players audio instructions like F1 drivers? Thanks in advance for clearing this up