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Notes for the Instructor

Forensic scientists use principles of physics in almost every investigation. Understanding force and motion can help investigators when analyzing car crashes, blood spatter, wounds on victims, and firearm ballistics. Investigators can figure out how fast vehicles were going before they collided, determine the height of a criminal based on the wounds he inflicted, or decide from how far away a bullet was shot and whether or not the shooter was standing still or moving. While many of these scenarios are too severe for a young audience, it is important for students to know the role that physics in general, and force and motion in particular, play in solving many crimes.

Young students have had a lot of experience with force and motion during their everyday lives and play. Whether it is asking someone to push them on a swing, opening or closing a door, toting a load of dirt in a wagon or kicking a ball during soccer, forces are at work everywhere for children. We can tell by their actions and movements that they know intuitively what forces are and how they work. This activity will provide students with language to describe and talk about what they experience every day. Mainly that:

• Forces are pushes and pulls that act on an object • Forces can change in strength and direction • Forces can speed up, slow down or change the direction of an object’s motion • The direction of the object will follow the direction of the force • When two objects collide, a force acts on both objects

Students will focus on the fallen model skeleton in Mrs. Hawkins’s classroom to imagine (and predict) what happened on the day Alice was taken. By running a simple experiment, students will make a connection between a force (a rolling ball) and the resulting movement of the object (a model figurine). They will use this knowledge to determine which way the perpetrator was moving on the day Alice was taken. Knowing the directionality of movement will guide students to deduce the entrance used by the thief, and move them one step closer to finding Alice.