Andrew Roberts, veteran math teacher, instructional coach, teacher trainer and data guy says that there is just no arguing with results when it comes to inquiry-based vs direct instruction.
Resources:
Connect with Figure Math
Angela Duckworth's book - Grit: The Power of Passion and Perseverance
Angela Duckworth's TED Talk on Grit
Carol Dweck's book - Mindset: The New Psychology of Success
Carol Dweck's TED Talk on Mindset