<span style="color:#ff0000;">1-I did not play my best so that the child could beat me.</span><br/><br/><span style="color:#800080;">2-I did not play my best<b>,</b> so that the child could beat me.</span><br/><br/><span style="color:#ff0000;">3-I did not play my best for the child to beat me.</span><br/><br/><span style="color:#800080;">4-I did not play my best<b>,</b> for the child to beat me.</span><br/><br/><span style="color:#ff0000;">5-I did not play my best in order for the child to beat me.</span><br/><br/><span style="color:#800080;">6-I did not play my best<b>,</b> in order for the child to beat me.</span><br/><br/>Are these sentences correct?<br/><br/><u>They are all supposed to mean:</u><br/><br/>For the child to beat me, I did not play my best.<br/><br/>My intention was for the child to beat me and that is why I did not play my best.<br/><br/>It seems to me that the comma is option in the first pair but necessary in the other two pairs.