Shape of parabola
Steps:
1. On a wax paper draw a line.
2. Take a point A outside the line.
3. Fold the paper so that the point А is on the line.
4. Repeat the step 3 for various positions of A on the line.
5. Which shape can you see?
Geogebra construction:
Folding a paper so that point A is on the line means drawing the perpendicular bisector of point A and and a point on the line.
See the construction below.
What is the focus?
What can you see if point A is near (far from) the line?
What can you see if point A is on the line?