Please check out these helpful mental math videos:
Counting on:
https://www.youtube.com/watch?v=MW36KfwFHec&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=67
Creating an easier problem:
https://www.youtube.com/watch?v=XCmr7-55aNs&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=66
Making a Ten:
https://www.youtube.com/watch?v=LzqCG0O8bmo&index=67&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Using the relationship between addition and subtraction:
https://www.youtube.com/watch?v=G_proYf2zq8&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=69
Using a 100's board to add and subtract:
https://www.youtube.com/watch?v=MFhajDPijuA&index=70&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Using a Numberline to add or subtract:
https://www.youtube.com/watch?v=JNHCdTZntYE&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=71
Represent a numberline with a place value drawing:
https://www.youtube.com/watch?v=rTSeDaXCUZk&index=74&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Write a number in expanded form:
https://www.youtube.com/watch?v=ZIDN3SobcCg&index=75&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Pairing objects to decide if they are even or odd:
https://www.youtube.com/watch?v=ZIDN3SobcCg&index=75&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Counting on:
https://www.youtube.com/watch?v=MW36KfwFHec&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=67
Creating an easier problem:
https://www.youtube.com/watch?v=XCmr7-55aNs&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=66
Making a Ten:
https://www.youtube.com/watch?v=LzqCG0O8bmo&index=67&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Using the relationship between addition and subtraction:
https://www.youtube.com/watch?v=G_proYf2zq8&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=69
Using a 100's board to add and subtract:
https://www.youtube.com/watch?v=MFhajDPijuA&index=70&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Using a Numberline to add or subtract:
https://www.youtube.com/watch?v=JNHCdTZntYE&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz&index=71
Represent a numberline with a place value drawing:
https://www.youtube.com/watch?v=rTSeDaXCUZk&index=74&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Write a number in expanded form:
https://www.youtube.com/watch?v=ZIDN3SobcCg&index=75&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz
Pairing objects to decide if they are even or odd:
https://www.youtube.com/watch?v=ZIDN3SobcCg&index=75&list=PLNDkuWRw1gGRpuFSgmHjf07KamFfjq8Gz