Learning Resources ColorMix Sensory Tubes. Help children practise managing their emotions with this mesmerising set of colourful tubes. Shake a tube to mix the colours, and then watch the calming effect as they slowly separate back into their original colours. Tubes are securely sealed, and the square-end caps mean children can use them vertically and horizontally. Tubes measure 20cm H x 4.5cm W. Ages 3+.