How many projects have their resources provided by the vendor Lakeshore Learning Materials and are created by a teacher with a doctor degree?
Lakeshore Learning Materials is vendor_name;  teacher with a doctor degree refers to teacher_prefix = 'Dr.';
SELECT COUNT(T1.projectid) FROM resources AS T1 INNER JOIN projects AS T2 ON T1.projectid = T2.projectid WHERE T1.vendor_name = 'Lakeshore Learning Materials' AND T2.teacher_prefix = 'Dr.'