Lying

Talk to me more about lying please. My son has a history of lying. He even knows he lies. He told a couple thousand people at his baptism about it. Here is the latest occurrence and I need to know how I could have, or should have, handled it better. He chose this particular day as Math day. I laid out his math and math games and told him every 10 minutes that I was only free in the morning to help him and play games because we had a busy afternoon and would not be home. He got annoyed. Told me to stop telling him. Told me he would do his Math on his own, stated many times he did not need me. I reminded him that in the past he would cry, yell, and tell me what a horrible mother I was for not helping him IF he decided to suddenly do his Math in the afternoon. I asked if I should record him saying that he would not do this and could do Math on his own. I had him look me in the eye. All the other children heard this stated. He refused my help. Fast forward. I am leaving for swimming with child number 5. He was told if his Math was not done then he would need to stay home and complete it. This was explained in the AM. He said "You did not tell me that! I need your help with Math. I cannot do it without you." Enter sobbing, crying, hysterics and him calling me a liar. Every child agreed that I had pre taught the heck out of this scenario in the AM. He got into the car anyway. I then yelled at him and said that I was done with the lying. And that as a consequence for doing all the things I asked him not to do: crying, not doing math, getting into the car, blaming me, etc., he was choosing a 24 hour loss of privileges. I told him, well yelled at him, that I was done with the lying and I was not going to trust his words again because I pre-taught the entire scenario several times and he still lied. He asked if he could get out of the loss of privileges if he self-reported. I told him no, but that it would allow the 24 hour loss of privileges to start immediately. He self reported he lied. His lying is beyond aggravating to his father and I . He also told me that you would say he was too young at 8 for 24 hours, that you would say it should be 8 hours. He said in a previous call you said 8 hours. He told me to ask you if it should be 8 or 24, want me to ship him to your house so you can clarify things for him? Help. How could I have done this better? This child is loving, full of laughter, talkative, and lies.