What do systematic reviews say?

Receptive L2 proximal vocabulary (understanding of words taught in the intervention) · second language (L2) learners up to six years of age

Receptive L2 distal vocabulary (understanding of words not included in the intervention) · second language (L2) learners up to six years of age

Expressive L2 proximal vocabulary (expressing or producing words taught in the intervention) · second language (L2) learners up to six years of age

Expressive L2 distal vocabulary (expressing or producing words not taught in the intervention) · second language (L2) learners up to six years of age

Mean length of utterance (MLU) · second language (L2) learners up to six years of age

L2 listening comprehension · second language (L2) learners up to six years of age

L2 narrative skills · second language (L2) learners up to six years of age