1. Fill the bottles up with water and liquid soap. Add different coloured food dye and use them to teach your kid about colours. Amuse them with bubbles when you shake the bottles.
2. Put different types of grains (rice, lentils, red beans, barley) inside your bottles and make milk bottle maracas for your kid. Teach them about the different types of grains and different sounds they make when shaken. Make music together!