This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.
Comments about Including the Crosscutting Concept
Students make predictions based on changes they will make to the model, then observe the effects of their changes, but the phrase “cause and effect” is not mentioned in the student handout. The teacher would need to guide students to the understanding that the independent variable (force from the "people") is the cause, and the dependent variable (motion) is the effect. This discussion might also be a good time/place to point out that the distance of people along the rope turned out to be a red herring (not a cause of change in motion), since the "people" in the simulation are directly attached to the cart by the rope no matter where they are physically standing. Students may also equate the different sizes of the "people" in the simulation with different masses, rather than different forces. Make sure to point out that the force arrows get labeled in Newtons, not kilograms. Relating the simulation to real scenarios may also be helpful here - have one student pull or push something hard and then pull or push the same thing gently, to show that the mass of the student is not directly related to the force he or she applies - the person's mass is not the cause of the motion.