Learning Resources Big Time Learning 12-Hour Demonstration Clock. This oversized clock is ideal for front of class teaching of time. Hidden gears maintain correct hour and minute relationships as you demonstrate time-telling concepts to your primary learners. This teaching time clock is made from durable plastic and has easy-to-read hour and minute markings. Hands are colour-coded to aid the teaching of hours and minutes. This large demonstration clock features removable stand and comes with a helpful teaching guide. Clock measures 34 cm. Suitable for ages 5 years and above.