Need help cooking problem on sims3 mobile!!!!

Hello,

I've got up to the last skill point in cooking but i don't know how to complete the last point?! I don't understand that if i keep my pots from boiling over but i still seem to lose and i don't know why? Do i have to keep the pots at the same level as each other or one low and one high? I'm so confused and annoyed at not being able to get the last point can anyone help me pleeeeease?