They should be able to identify the simple machines and how energy is transferred from on to the other. If you want to make it a contest, see who can crush the most grapes in a minute. Class winners could compete with one another or with other schools. Experiment is logical and clear. Data is recorded and thoroughly analyzed.
Diagrams are present.
Conclusions thorough and thoughtful. 6 Competent Completes all steps. Experimental procedures lack thoroughness. Data is recorded, analysis not complete. Conclusions too brief.