These days we like to ask our boy do counting. Not using any math books. Since he knows the sequence of 1 to 10, we begin to introduce Math in his daily life. Like during reading, we ask him how many birds(image) on the page; during mealtime, we ask him how many plates on the table; during playtime, we ask him how many balls in the basket; during shopping, we ask him how many tins of milk powder in the cart. Let him count anything he can see and/or touch even though sometimes he makes error. Through many trials and errors,he picks up faster.
The most simple one, we just ask him to count how many fingers on his hand(s). (Note: This can be done anytime and anywhere like during a car ride or while queuing at the cashier) In my opinion, my boy is still young, he should enjoy learning process through fun methods. We try to promote "Zero Stress" in his early learning environment.