This Khan Academy video plays with slightly larger fractions (e.g. 48/64) but explains the concept very clearly and haso online practice exercises linked in the video description.
Great for getting an initial understanding. The video explainers are really fun and then there's a simple quiz at the end to test understanding, that can be complemented by practice worksheets from elsewhere.
2 pdfs of printable exercise sheets and 1 powerpoint presentation for practice. The pdfs go through different levels of fluency (e.g. developing vs greater depth) to help students at different levels.
Very visual worksheet with pie charts which will help students to understand why one fraction is a simplified version of another as they work through it.
Video with an ingenious way of teaching about simplifying fractions - teaching students how to 'complicate' simple fractions (e.g. turn 1/2 into 12/24) and then how to undo their own mess!
Full unit on simplifying fractions including explainer videos and online and printable exercises of different difficulties. Thank you Maths Salamanders!