Alexander Graham Bell played with sound waves using a phonautograph which recorded sound onto paper. Through experimenting with transmitting sound waves, he invented the telephone. Thomas Edison had a playful attitude towards experimenting with chemicals in his laboratory, inventing the light bulb. Lego's plastic bricks were invented by Ole Kirk Christiansen after starting with wooden toys, and Google was created by Larry Page and Sergey Brin who played with search engine ideas as students and developed the algorithm powering the popular search engine.

1. Alexander Graham Bell: The
inventor of the telephone,
Alexander Graham Bell, was
known to play with sound waves
and experiment with different
ways to transmit them. He often
played with a "phonautograph," a
device that would record sound
waves onto a moving strip of
paper. This experimentation
eventually led to his invention of
the telephone.

2. Thomas Edison: Thomas Edison, the
inventor of the light bulb, was known to
play with chemicals and conduct
experiments in his laboratory. He was
known to have a playful attitude towards
experimentation and was often quoted as
saying, "I never did a day's work in my life;
it was all fun."

3. Lego: Lego, the popular building toy, was invented by
Ole Kirk Christiansen, a Danish carpenter. He began
making wooden toys in 1932 and started producing
the plastic bricks that we know today in 1949. Lego is
now one of the most popular toys in the world and
has been used for educational and research
purposes and play.

4. Google: Larry Page and Sergey Brin, the
co-founders of Google, met while they
were graduate students at Stanford
University. They were both working on a
research project that involved playing with
ideas and concepts related to search
engines. They continued to play with
these ideas and eventually developed the
algorithm that powers Google, now the
world’s most widely used search engine.