Working on expression can be worked on systematically. You can start with one word answers, phrases, and sentences and progress to story telling and short answers.
Sequencing Cards: This set works fairly well with 8 12 year olds.
Exanding Expression Tool: Multisensory system for building descriptive language
Dixit: A very creative story telling game – great for creating stories from non-linear prompts
Snapshots: Photo collection with multi-age photos and critical thinking questions. Can be adapted to many uses.