Curated OER
The Part-adder 1
Second graders investigate the addition of whole numbers. They mentally perform calculations involving addition and subtraction. They make sensible estimates and check the reasonableness of answers.
Curated OER
Mental Multiplication
Students discover how to multiply large numbers in their heads using some simple techniques. They understand that multiplying by 5 is done by multiplying by 10 and cutting the answer in half. They also understand that multiplying by 9...