Learning Resources Metric Weight Set. This best selling Metric Weight Set from Learning Resources is an ideal maths accessory! The set is great for introducing weighing and measuring concepts to young learners who want to get hands-on with maths. The set includes twenty 1g, twenty 5g, ten 10g and four 20g weights in a handy storage tray. Weights come in yellow, green, blue and red – a different colour for each weight. Set of 54. Suitable for ages 8+.