Abdul Halim Abdullah and  Nur Liyana Zainal Abidin and  Mahani Mokhtar,  Using Thinking Blocks to Encourage the Use of Higher Order Thinking Skills among Students When Solving Problems on Fractions .   journal   = {International Journal of Educational and Pedagogical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    January 2017, vol. 122(2). 342 - 348
    [viewed 19 April 2021]. Available from: https://publications.waset.org/pdf/10006278.