This art lesson introduced us to Bas Relief (pron. baw-relief). This is a sculpture technique in which the design is just barely more prominent than the background.
Example

I told the boys to keep the design simple for their bas reflief project.
‘A’ made a cactus…

‘R’ made a race car going over the finish line and the man is holding a banner and reaching for a trophy….

Note to self: Next time, define ‘simple’…