Responses to Braitenburg's "Vehicles"
Responses to Resnick's "Behavior Construction Kits"
Is the subject matter well-suited to a science kit? (As opposed to some other medium -- toy, museum, field trip)
Is the kit designed in an age-appropriate way? Does the level of writing fit the level of construction activities? Is the writing informative -- both in terms of instructions and science?
Are the components reusable? Are there enough materials to do (or maybe redo) all the activities? Are the components available elsewhere?
How attractive/sturdy/reusable are the kit's results?
Does the kit inspire curiosity? Does it encourage experimentation?
Are there obvious computer extensions?