Together, we drew a mind-map of their interpretation of what assertiveness meant. This all to common view of assertiveness is not the kind of behaviour that is being endorsed. Assertiveness is about respect, both for ourselves and others. It is also about taking responsibility for ourselves and helping others do likewise. As we grow up there are many pressures on us to behave in non assertive ways.
Aggressive behaviour disregards the rights of others.
It can be threatening or punishing, perhaps with the aim getting one's own way. This may be achieved in the short term, but the relationship will suffer in the long term. Submissive or passive behaviour disregards our own rights. It allows others to take advantage of us. We may see ourselves as helpless victims without any control over what is happening to us.