Benchmark 11B
Common Themes: Models
Grades 3-5, page 268

Seeing how a model works after changes are made to it may suggest how the real thing would work if the same were done to it.
 

NSES Content Standard A 
Science as Inquiry: Understanding about scientific inquiry
Grades 5-8, page 148
Scientific explanations emphasize evidence, have logically consistent arguments, and use scientific principles, models, and theories. The scientific community accepts and uses such explanations until displaced by better scientific ones. When such displacement occurs, science advances.

NSES Content Standard E 
Science and Technology: Abilities of technological design
Grades 5-8, page 165
Design a solution or product. Students should make and compare different proposals in the light of the criteria they have selected. They must consider constraints--such as cost, time, trade-offs, and materials needed--and communicate ideas with drawings and simple models.

See also the general discussion in Unifying Concepts and Processes: Evidence, models, and explanation.