The first two files have sliders for all the variables. The last several do not. I required each student to come up with 4 equations. Two from the easy column and two from the not-so-easy column. We were able to complete the modeling portion lesson and a summary classroom discussion within two class periods. Not bad. Not bad at all.
Geogebra Files with Sliders (easy)
Geogebra Files without Sliders (not so easy)