when the teaching gets tough

I am not sure does it applies to all parents but to us, it's really a big challenge to teach our own kids. Especially when it comes to academic guidance. Just for a P1 curriculum, we find that its way too advance and wordy for them to comprehend. Otherwise, is that both of my hubby and I underestimate the Singapore Education System. The curriculum that we are teaching our son today is what we are suppose to learn at P3-P4 level. It doesn't help when the P1 boy is not paying attention much and having the silent "strike" in him to not do his work. When the teacher returned the semester worksheets to us, we almost have a shock! Our boy's work have slipped to below expectation. It makes us think, if the change of form teacher, does it affect the child's school life as well? He was once a confident, obedient boy in the first half. Now, he is more careless, inattentive, child who lies about his school homework. No amount of disappointment can bring back the child's progress. Even when I teach him, I felt like vomiting blood. No kidding. Exasperated when he doesn't take the school work seriously. He tends to complete one sum in 3 mins, which can be done in half a min. At our wits ends' about educating this boy. I am afraid of the little sister of him going to take after his laziness and therefore, starts to drill her on her attention span with academic as well as attitude towards school. Wish this trying phase goes pass soon.