Elicited production
Participant	DA			PM			JJ
Time point	Pre	Mid	Post	Pre	Mid	Post	Pre	Mid	Post
Auxiliary declaratives	0.75	0.77	0.73	0.45	0.13	0.27	0.91	0.94	1.00
Auxiliary questions	0.00	0.70	0.70	0.00	0.86	0.91	0.67	1.00	1.00
3s	0.31	0.00	0.25	0.69	0.86	1.00	1.00		1.00
Past –ed	0.30		0.20	0.33	0.60	1.00	0.00		0.00
Copula declaratives	0.87	0.71	0.67	0.92	1.00	1.00	1.00	1.00	1.00
Copula questions	0.00	1.00	0.67	0.00		0.57	0.00		1.00
Language sample
Participant	DA			PM			JJ
Time point	Pre	Mid	Post	Pre	Mid	Post	Pre	Mid	Post
Auxiliary declaratives	0.69	0.75	0.80	0.71	0.63	0.48	0.53	0.75	0.80
Auxiliary questions	0.50	0.80	0.91	1.00	0.50	0.57	0.78	1.00	1.00
3s	0.02	0.00	0.07	0.45	0.60	0.29	0.96	0.63	0.91
Past –ed	0.00	0.00	0.20	0.11	0.50	0.86	0.53	0.75	0.40
Copula declaratives	0.44	0.67	1.00	0.83	0.94	1.00	0.86	0.79	0.89
Copula questions	0.81	0.88	0.80	1.00	0.86	1.00	0.79	0.94	0.94
Sentence imitation
Participant	DA			PM			JJ
Time point	Pre	Mid	Post	Pre	Mid	Post	Pre	Mid	Post
Auxiliary declaratives	0.60	0.60	0.60	0.83	0.50	0.70	0.87	1.00	1.00
Auxiliary questions	0.07	0.30	0.70	0.67	0.40	0.90	0.90	0.90	1.00
3s	0.33	0.20	0.20	0.80	1.00	1.00	0.80	1.00	1.00
Past –ed	0.40	0.20	0.20	0.67	0.20	0.80	0.80	1.00	0.80
Copula declaratives	0.50	0.70	0.60	0.83	1.00	0.80	0.90	0.80	0.90
Copula questions	0.13	0.30	0.60	0.87	0.70	0.80	0.97	1.00	0.90

Note. Pre time point includes average of all baseline measures. Blanks in the table represent less than three attempts at production of the grammatical structure.