How to make kids happy for free?

I always envy kids for their superabundant energy. They seem they are unstoppable!
If you are parents and wonder where to take your kids to, there are some places that you can take them and spend time there without spend so much money or even for free.
These are some recommendations around Tokyo area.

*Tokyo Water Science Museum (For Free)
Location : 3-1-8 Ariake Koutou-ku, Tokyo (8min walk from Kokusai-tenjijo Station)
Opening Hour : 9：30am-5pm (Last entry is at 4:30pm)
Closed : Every Mondays (If the Monday is national holiday, the next day is closed),year-end and New Year Holidays
HP : http://www.mizunokagaku.jp/

*Gas Science Museum (For Free)
Location : 6-1-1 Toyosu Koutou-ku, Tokyo (6min walk from Toyosu Station)
Opening Hour : 10:30am-5pm (Lase entry is at 4:30pm)
Closed : Every Mondays (If the Monday is national holiday, the next day is closed), year-end and New Year Holidays
HP : https://www.tokyo-gas.co.jp/en/?_ga=2.94105621.927382830.1602818665-337603562.1593418268

*Adachi Children Future Creation Hall
Location : 1-3-1 Kurihara Adachi-ku, Tokyo (3min walk from Nishiarai Station)
Opening Hour : 9am-9:30pm
Closed : Second Monday of the month, and some other days according to facility schedule.
HP : http://www.galaxcity.jp/modules/site/index.php?action=CatView&cat_id=1
There are many different events are happening at this facility. Please check the schedule and what kinds of event are available in the website.

*Toshiba Science Museum
Location : 72-34 Horikawa-Cho Saiwai-ku, Kawasaki, Kanagawa (1min walk from Kawasaki Station)
Opening Hour : 9：30am-5pm (10am-7pm on Sat, Sun and national holidays
Closed : Every Mondays (If the Monday is national holiday, the next day is closed)
HP : http://toshiba-mirai-kagakukan.jp/en/index.htm

*JAL Sky Museum
Location : Haneda Airport JAL maintenance center 1 (2min Shin Seibijo Station)
Courses :30min(Exhibition area only) 40min(airplane hangar area) 30min( Aviation classroom) coursecourse. You need to reserve one of the coursed beforehand.
Closed : year-end and New Year Holidays
HP : https://www.jal.co.jp/kengaku/

*Edogawa Animal Park (For Free)
Location : 3-2-1 Kitakasai Edogawa-ku, Tokyo (15min walk from Nishikasai Station)
Opening Hour : 10am-4:30pm (9:30-4:30 on Sat, Sun and national holidays) *It’s till 4pm between November and February.
Closed : Every Mondays (If the Monday is national holiday, the next day is closed), year-end and New Year Holidays
HP : http://edogawa-kankyozaidan.jp/zoo/

*Itabashi Kids Animal Park (Kodomo-zoo Motozono in Higashi-itabashi Park) (For Free)
Location : 3-50-1 Itabashi Itabashi-ku, Tokyo (10min walk from Itabashikuyakushomae station)
Opening Hour : 10am-4:30pm (10am-4pm between December and February)
Closed : Every Mondays (If the Monday is national holiday, the next day is closed), year-end and New Year Holidays
HP :http://1000enpark.com/park/tokyo/itabashi/kodomo.html

*International Library of Children’s Literature
Location : 12-49 Ueno Park Taito-ku, Tokyo(10 minutes’ walk from JR line Ueno Station ,Park Exit)
Opening Hour : 9:30am-5pm (Library)
Closed : Every Mondays, national holidays (except Children’s Day on May 5), year-end and New Year Holidays and the third Wednesday of every month (for refiling)
HP : http://www.kodomo.go.jp/english/index.html

◆Search site of free facility◆（Japanese only)
http://iko-yo.net/facilities?tags%5B%5D=%E7%84%A1%E6%96%99%E3%81%A7%E9%81%8A%E3%81%B9%E3%82%8B

◆Free facility in Tokyo◆（Japanese only)
http://season.enjoytokyo.jp/free/