Hi V.,
Thanks for the clarification!
Bruno Bettelheim ("A Good Enough Parent") suggests that tantrums (what you are seeing with throwing objects and biting himself) are often caused precisely by what you describe: frustration. His proposed remedy is to watch when these situations are beginning to escalate, to offer the child something they 'can' do successfully. Part of what's hard about being a toddler is that they have it in their heads that they *should* be able to do things in an 'ideal' way-- by this, I mean that blocks, once stacked, 'should' stay up; legos 'should' click together. (Does he have the larger legos, which are easier to stack? Making sure he has age-appropriate materials will help.)
When I see children frustrated with their toys, I try to offer some empathy and distraction. "You know, those silly blocks want to fall down again. Can you help them fall over here?" (here, he directs *how* the blocks will fall and becomes an active participant in 'making' the blocks do something they are going to do anyway. "The blocks want to fall down. Let's make a line of them, like a train." (here, we redirect the play to something that the child has more control and capability over) "Wow! You are so mad at those blocks. You really wanted them to stay up! Let's tell the blocks 'Blocks, I'm sad you aren't staying up! I want you to be tall!' Let's see how tall YOU are. Stand against that wall and we'll make a mark. Now let's get the measuring tape..." (here, we've provided empathy by verbalizing the child's feelings, and then employed a simple redirection of asking the child to do something he's capable of which is also a distraction. It's totally worth the expense to get a small 6' tape measure too, for him to play with.)
It's Really Important NOT to ask "do you want to do X?" when we are trying to redirect when they are frustrated. Being that the child is a toddler (this is the prime age for practicing "no!" ) and that you are being assertive and proactive, do not ask for their child's yes/no answer, just move them through the moment. Heading tantrums off at the pass is the right time for us to show that we are in charge of the situation and have confidence that moving to the next activity is the right thing to do. If the child says they want to do something different, that's fine, so long as they aren't going back to the same frustrating activity. And this isn't a time to have them 'clean up' the frustrating toy. This is a time to get them settled on the new activity and do the cleanup yourself. I've learned this one over time. Their heads can only be in one 'place' at a time, so once we've moved them on, don't call them back.
I hope this helps. If your son does have a full-on tantrum, do give him time to cool off in a safe place, and try to offer the empathetic piece. Children who are frustrated and angry will bite themselves, and that's anger turned within, so you might think about offering verbalization as much as you can through modeling those words, so that he can direct the anger at the object. You can also give him substitutes-- when he wants to throw blocks, offer soft balls (have house-safe balls available in each room he plays in), or paper to crumple and throw. Kids need tactile ways to expend that angry energy.
Lastly, there's a great Mr. Rogers song called "What do you do with the mad that you feel?" that's good to learn. (It's on both the "Adventures in Friendship" and "What Do You Do With the Mad That You Feel" videos; the second, though, is a bit heavier and more direct, I like the first better, as does my son.) The song suggests offering playdough, seeing how fast you can run, punching a bag/pillow, and suggests that we can stop ourselves from hurting ourselves or others when angry. Gives a lot of good language for those feelings, too.
