Science Fans - Use Discount Code 'IXS2016' to save 15% on Octagon Studio's 4D Flashcards, our own Newton's Colour Wheel, cool Diffraction Glasses and our new USA/UK Eclipse Glasses. As seen on the BBC The Gadget Show and Thatcher Joe's youtube channel. Great resources - Excellent gifts. NB. Amazon Fire HD and Huawei devices require a workaround to add Google Play Store.