Conserving sets means that a person can look at a grouping or a set and identify how many there are without individually counting them. (i.e. three fingers that are held up) When a child is unable to do this, they cannot memorize math facts since memorizing is associating an abstract number with a concrete set. Many teachers as well as parents fail to recognize the root cause of this memorization problem. AND no amount of practicing, bribing, yelling, or pulling out your hair will change the situation. So what can you do?
First of all, the problem must be identified. Use a dice and see if the child must count each dot on each face. Try holding up fingers or laying out sets of candy (M&M's - yummy!) or using dominoes. Put five beans in a container, and ask the child how many are in the box. (They may count them the first few times.) Take them out, and put them back in. Ask the child again how many there are. If, after several times, s/he is unable to recognize the set as a whole, then s/he cannot conserve sets.
How do you help such a child? If you have small children at home, begin the conservation of sets by holding up various combinations of fingers. My granddaughter just turned four; so, we worked on holding up two fingers on one hand and two fingers on the other; then one and three fingers, and of course, four fingers. I also like to use dominoes. They already have set groupings which can be identified, added, subtracted, and even multiplied. A dice is great because the child thinks you are playing a game, not doing math. Roll one dice, and ask the child to identify the set of dots. Try the bean idea, but continue to change the number of beans in the box. My granddaughters love the candy idea because they are allowed to eat them when we are done. (All children need a little sugar now and then even though their parents try to control the intake. I love being a Grandma!)