As an old quote from DanielLC says, consequentialism is "the belief that doing the right thing makes the world a better place". I now present some finger exercises on the topic:

1. Is it okay to cheat on your spouse as long as (s)he never knows?

2. If you have already cheated and managed to conceal it perfectly, is it right to stay silent?

3. If your spouse asks you to give a solemn promise to never cheat, and you know you will cheat perfectly discreetly, is it right to give the promise to make them happy?

4. If your wife loves you, but you only stay in the marriage because of the child, is it right to assure the wife you still love her?

5. If your husband loves you, but doesn't know the child isn't his, is it right to stay silent?

6. The people from #4 and #5 are actually married to each other. They seem to be caught in an uncomfortable equilibrium of lies. Would they have been better off as deontologists?

While you're thinking about these puzzles, be extra careful to not write the bottom line in advance and shoehorn the "right" conclusion into a consequentialist frame. For example, eliminating lies doesn't "make the world a better place" unless it actually makes people happier; claiming so is just concealed deontologism.