A unit I started near the end of my practicum was force and motion.  My school advisor wished for me to start the unit and she would continue it to the end of the year.  One particular lesson to note was the lesson on gravity.

1. I had the special person hold one end of a string.
2. I attached the other end of the string high on the wall.
3. I pulled a basket up to the top of the string.
4. I let the basket go.
5. I asked the students what happened and scaffolded until I got the answer, gravity.

The students absolutely loved experimenting with gravity and some children came up with amazing questions about gravity.  Due to the time limit I did not get to explore these questions with the students.  However, if I had had the time we would have delved deeper into the concept. I could have also tied in an introduction to the solar system by discussing the different amounts of gravity on each planet.