Neil and Pippa explore the effectiveness of language learning apps like Duolingo, Babbel, and Busuu. They discuss research suggesting that while apps excel at implicit learning, adults benefit from a mix of explicit grammar instruction and immersion. The episode highlights a study comparing app users to classroom students, noting that apps improved written skills while classes boosted listening abilities. Ultimately, the hosts recommend combining app-based repetition with human teaching and varied practice to achieve the best language learning results.