So many experiments didn't work in those 100 in 1 kids of the early 80's, lions pondered actually obtaining either an intact kit or enough documentation to try building all the experiments which didn't work.  

The big failures were anything which depended on a single transistor oscillator, the tone generators.  Others were ones a young lion just wasn't smart enough to know the purpose of, like an amplifier or a filter.

The crystal radio was the only one which worked, but it would be amusing to try to extend with an amplifier.  Filters were the most mundane, since they didn't blink or make noise, yet they evolved to the most important concepts 40 years later.