On my recent South African trip, I visited the Sci-Bono Discovery Centre in Johannesburg. This science museum is a little like Questacon in Canberra. Sci-Bono’s strengths are the large number of well-built interactive exhibits and the large number of helpful staff. Exhibits concentrate mostly on physics and technology. All ages from toddlers to adults are catered for.
The Sci-Bono Discovery Centre is not free, but is value for money. I enjoyed it, and Tripadvisor gives it 4.5 stars. Sci-Bono is active on Facebook and Twitter.