Black White Card app for iPhone and iPad
How to use black and white card:
1. Hold the card about 30cm away from the baby.
2. Slow movement causes the baby to follow.
3. Switch to the next card after the baby sees the card.
Black and white card training time:
1. Use 5 to 10 cards at a time.
2. Train no more than 5 times a day and no more than 15 minutes.
Notes for black and white cards:
1. Use it when your baby is in good physical and mental state.
2. Once the baby is in bad condition, stop immediately.