1. To compare the size, quantity, length, height and weight of two things, we should take one as the reference or one as the standard, and then compare them, so that we can say that the other thing is bigger or smaller, more or less than the standard one.

2. Add the two numbers. Appendix+Appendix = and: 3+ 13= 16, where 3 and 13 are addends and the sum is 16.

Addition without carry and subtraction without abdication within 3.20.

4. When the classification standard is known, we only need to judge which category a given thing belongs to, and then put things of the same kind together.

A cylinder is like a pillar. It has two upper and lower round faces, which are the same size, so it can be used to draw a circle; The other side is curved, so we can put the curved side on the table and roll it.