In my last post, I pondered how to integrate skills across math, ELA, and science in a lesson about falling objects. The mathematics content quickly became a little complicated for fifth grade. What other ways can we represent data to make it more accessible?
My next idea was to look at a ball drop over a longer distance. I found a video of a ball dropped from the roof of a building that was a sample video in Video Physics from Vernier Software. I used Video Physics to mark the position of the ball in every 10th frame of the video. These marks are a visual representation of the data.
Students can look for patterns in the spacing of the marks. They should notice the marks get farther apart as the ball falls. How is this evidence of the direction of gravity?
The person released the ball and it fell. The observation that the ball moves downward is evidence that some force pushes or pulls down. But what about after the release? Is that force still pushing or pulling down? How do we know?
The pattern of the marks gives us clues. The marks show the ball position at evenly spaced time intervals. The ball moves farther during each time. This means the ball is moving faster. What made it move faster?
Teacher content knowledge
Here is a little refresher about elementary physical science and the topic of forces and motion. Students learn about forces and motion in several grades.
- In kindergarten, students explore the effects of different strengths and directions of forces on motion. They also compare design solutions for changing the motion of an object. (K.PS2-1 and K.PS2-2)
- In Grade 3, students investigation the effects of balanced and unbalanced forces on the motion of an object. They also learn to use patterns of motion to predict future motion. (3.PS2-1 and 3.PS2-2)
In Grade 5, we ask students to transfer knowledge from their prior observations of contact forces (pushes and pulls) to a non-contact force (gravity). They should already know that to make something keep getting faster (accelerate) requires continued pushing or pulling in that direction from explorations in kindergarten and grade 3. Applying that to the falling ball, students can infer that something must be pulling or pushing the ball toward the ground to make it go faster.
Once students have made this inference, they are ready to learn about the concept of gravity. Gravity is different than pushes and pulls. The Earth pulls on the ball because the Earth is extremely large. The pull of Earth on objects is gravity.
When the person holds the ball, the forces are balanced. The upward force of the hands on the ball balances the downward pull of gravity. After the person releases the ball, the forces are unbalanced. The downward pull of gravity makes the ball speed up as it moves toward the ground.
The next step is for students to create an argument with grade-appropriate ELA skills. Those CCSS were listed in this post.
Did you find this post helpful? If so, let me know in the comments.