Learning Resources STEM – Sink or Float Activity Set. Specifically designed to engage children in science, technology, engineering and maths, primary learners can get hands-on with STEM learning with this colourful Sink or Float Activity Set! Children can explore early physics by bringing investigations to life, recording data as they go in order to find an optimum solution. Set focuses on a variety of key science concepts including buoyancy and density. Eye-catching set includes two piece floating raft, weighted balls and stars and 10 activity cards and activity guide with reproducible materials. Suitable for ages 5+.