Here is a classroom activity I used with my IB Maths HL students to practice the double and half angle formulae. It is a set of dominoes that the student has to connect from the Start card to the Finish card by solving problems with the double and half angle formulae. The question on the right (above) needs to be connected to its answer on a another card. The answer on the left fits with a different question. I know that the students have completed the task correctly if all the cards are used in a chain from Start to Finish.
I made this activity with Formulator Tarsia, brilliant free software for teachers. I have used it to make matching cards, dominoes, and hexagon puzzles. It’s designed for maths and it can handle maths notation including fraction, exponents, roots, integration, matrices, and so on. I converted the Tarsia file to a pdf using Cutepdf.