Introduction Textbook To The Oscilloscope　AKE-2001

A good introduction to the basics of oscilloscopes.
It covers proper handling of the oscilloscope, basic operations, technical terms and prior knowledge.

Spring Scale Cylindrical SAN -1 10 N/1 kg and others

Butterfly peas (pH indicator) 10 g　G40-5714

Like purple cabbage, you can easily make an indicator that changes color depending on the pH of the aqueous solution.
It is commonly known as a tea whose color changes with lemon.