Cuarto año: Adiciones y Sustracciones

Adiciones:

https://www.youtube.com/watch?v=oexd_Dfic_Q

https://www.youtube.com/watch?v=sahheRPwbZ8

https://www.youtube.com/watch?v=9dhz8RnzlZE

https://www.youtube.com/watch?v=db52lKGglhs

Sustracciones:

https://www.youtube.com/watch?v=42vjqtleG9E

https://www.youtube.com/watch?v=VrS6Zge37n0&t=331s

https://www.youtube.com/watch?v=OAr0Q1R1bCA

Doble y mitad:
https://www.youtube.com/watch?v=lNwH6Ic7IVo
https://www.youtube.com/watch?v=XLF6nN-11cA&t=122s

Resolución de problemas:

https://www.youtube.com/watch?v=ne4olKWASik

https://www.youtube.com/watch?v=xvyn-FfcQp4&t=104s

https://www.youtube.com/watch?v=xvyn-FfcQp4

https://www.youtube.com/watch?v=B2FgQNl_E-Y&t=38s