Hi NeoMaxi...
there are some brilliant suggestions above which look like a lot of fun for both of you to do. I thought some of these websites might help:
Oxford Own has games but also all sorts of suggestions for early years/ young readers/ mathematicians.
Link here: www.oxfordowl.co.uk/
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Snakes and ladders is brilliant for counting on skills and played backwards will help build those subtraction skills. If your DC is fine up to 6, then add a second die so they have to cope with numbers over 10.
we started out letting DDs count up (using fingers, toes, etc...) but then gradually encouraged them to do it in jumps (so 4 was = add 2 twice) and in their heads. When they get really good have them just do it in their heads.
When it's time for multiplication you can dust this off and try again - only play 2 -4 times up and down the board. You can either roll one or two dice at the start to chose multiple you're working (so if you roll 8 with two dice) all subsequent rolls are for what you multiply 8 by. This means you'll zoom up and down the board (thus the need to agree to complete the board 2-4 times.
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Mumsnet has a link to maths champs off there learning & resources page (under education). The link to 5-7 year old games is here: www.mathschamps.co.uk/games5-7?
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For reading - just keep it ticking along. Keep up a ritual of being read to and reading to your child every day.
Consider building in a trip to the local library into your week - they often have all sorts of reading activities over the summer & craft days.
If sounding out letters is the sticking point - consider getting some of the jolly phonics work books. They're effectively colouring books - which work on letter sounds systematically (your school is probably teaching phonetics with it or something very similar). There's also lots of writing practice with the books. We tried to link the sound (say 'ah' for a) with that nights reading - having DDs spot the letter and attempt the sound on easier words like (sat, cat, hat, an).
HTH