This text is taken from montessoriparenting.org.   Dr. Montessori famously and repeatedly stated that the child is his own teacher as he explores his world; however, he still needs the adults, from parents to family, teachers, and friends, to be his guides. We are to provide explanations, and boundaries, act as role models; and, at time, be the control that inhibits dangerous, undesirable or inappropriate behavior, to redirect the child’s energies or to deny him something he wants. More often than we might like, this does mean saying “no” to the child.

Psychology Today outlines when to say no to your child. 
1. Say no when their actions might hurt someone or break something.  Preventing harm is the number one reason to say no.

2. Say no when they could do it on their own.  Sometimes kids ask parents to do things for them that they could do on their own.

3. Say no when it’s a want, not a need.   We’re constantly bombarded with ads but buying everything that appeals isn’t the right way to go. 

4. Say no when plans change. Life happens. Even when we intend to do something our children want, sometimes circumstances prevent it from happening.

5. Say no when someone else’s needs (temporarily) matter more.  Kids are naturally self-centered, but considering someone else’s needs enables them to move past that. This kind of no helps children learn generosity.

6. Say no when you’ll resent doing something.  Resentment is poison in any relationship. It’s usually better not to do something than to do it with bitterness and anger. This kind of no helps children learn about healthy boundaries or compromise.

7. Say no when it’s against your values. We teach our children about our values through the choices we make.

There is absolutely nothing wrong with saying no to your child if it’s done with love.  Let them know that even with that no, you love them more than anything else in the world.