I'd try a balance of gross motor activities, fine motor activities and reading and arithmetic. Many of these activities are pre-math and pre-reading. Your child should also be well into learning to make choices and decisions.
These ideas cover from 24 months to five years. Do not expect your son to do all of these with any skill. You are building the skills.
Your son is starting to be ready physically to do physical activities like catching, throwing into a goal (like a large box on the floor), jumping, running, log rolling, riding a tricycle or even a two-wheeler with training wheels, swimming and even some sports. I was cross-country skiing (no poles) at that age. These activities help his brain to develop organising skills that are really important to the learning of academics.
Fine motor activities are also a great way to help your child develop important skills.
- Cutting with a plastic knife -- anything from playdough to bananas or bread are good choices. You do not want anything that resists cutting at the start because even a plastic knife can cut him. Spreading butter, or jam is also a good activity.Try to cut same sized portions or portions that share evenly with others.
- Pouring from one container to another. This is a great bathtub activity.
Pour to a line, divide water evenly between containers. Out of the bath, use paint or mild food colouring for a pre-science job. Blue + yellow makes what colour?
- using a pencil or fat marker to trace, make shapes, colour, and print or copy letters and shapes. Physically he may not be ready, so be encouraging and lavish with praise, while not expecting any sort of perfection.
- Matching -- match like items that are identical like socks, spoons and so on. Then match like items like cutlery and pots. The different cutlery goes into a cutlery group that then can be matched into the sub-groups of spoons, forks and so on.
- Sorting -- Blocks, beads, cars and so on can be sorted by colour, use, size. Toy animals can be sorted into domestic, farm and wild animals.
- 1:1 Correspondence -- "One to one correspondence is the ability to match an object to the corresponding number and recognise that numbers are symbols to represent a quantity. Young children often learn to count without having an understanding of one to one correspondence." (Kearns, 2010). This is an important pre-skill. The easiest way is to count objects by touching them. This allows the child the chance to understand that each number is representative of a thing. Rote counting doesn't make this connection.
Go on hunts for a specific letter. "I spy with my little eye -- an A." Look for them at the beginning of words to start but them point them out in the middle or end of words. Make the sound the letter make. (ă, ā) Point out upper and lowercase.
Read aloud and let your child read back to you by pointing out the words or letters.
- mapping and following directions, scavenger hunts -- the sort where you give a clue and the child solves the puzzle. ("It's in a room where there are curtains and water. It is behind something blue. It is something you use to fix your hair.")
- painting, clay and drawing, making art from found materials
- building / design: homes, castles, cities, dioramas, parks
- singing, making rhythms, learning to play a drum or triangle or recorder
- language -- this is prime time for learning a second language and vocabulary for your first language
In my own opinion any good teacher knows that children arrive with different levels of ability. The less ability a student has means they get more of the teacher's time. So I'd also teach your child to be self-reliant. Most teachers will not object if your child is quiet and busy and doing the same subject as the others. If that material is more advanced but the regular work is handed in and the child is not disrupting the class, it's a win.