In this portion, God tells us something so important that it is mentioned twice: Do not sacrifice anywhere but in the Temple. Why is this so important? Why can't the Israelites build an altar to God anywhere? It's similar to the idea of "appropriate restaurant behavior," a phrase your parents might have mentioned to you a few times.
It is not proper to run barefoot around the restaurant, waving a baseball bat and screaming: "Dodgers rule!" But you can do that, say, at camp or on the beach, if you are properly supervised. Same thing with the sacrifices. God and the Levites felt that sacrifices needed to be controlled and properly supervised, just in case the Israelites got out of hand and started acting in ways that might not be appropriate for Jews who follow God's commandments. And, they added, it is not the actual sacrifice of an animal that is important. It is the intention and the prayer that accompanies it. The moral of this story is: everything has its time and place.
Mitzvah Garden Nature Project
In this week's portion, God says to Israel: Choose the right way to live your life. If you follow the commandments, I will bring lots of rain and food to your land. So here is an idea for a mitzvah:
Plant a garden -- large or small. You will not get any rain in the summer, so help God by watering and weeding every day. When the flowers bloom, cut them, wrap them or put them in a vase and bring them to someone as a present. Maybe to your friend who needs cheering up or to your grandparents who want a special visit.