My child is 6 yrs he learns his school lessons late he is not sharp in memorizing what should i give him so that his memory power increases?

Time and practice: Just like he practiced walking and didn't just stand up one day and run around, his brain has to practice memorizing. Try different ways of presenting information. Some kids are oral learners (you can just tell them 2+2 is 4), while others are visual learners (show them 2 items and 2 more and then count all together are 4). Make learning fun, not a task or chore he is "good" or "bad" at!