Some examples

Beetles have elytra, highly scleritized front wings that function as armor to protect the membranous hind wings.  In beetles, these elytra fit together edge to edge which meet right down the center of thier backs.
Antennae are segmented.  Different insects have different numbers of antennae segments.  Bess bugs, a type of beetle (coleoptera) have 10 segments (see below).  Thus, they fit the description of "under 11 segments".  They're antennae are serrate (see glossary for other types of antennae).