Here's a quick, easy number sense activity you can do in the classroom or at home. All you need is a deck of cards.
Deal out 16 cards face up. Arrange them in a 4x4 box. This square is kind of a "number bank," which will be drawn from in the same way you would pick vocabulary from a word bank. Ask your student to create as many correct equations using the numbers in the "box" to fill boxes or spaces. You create a framework like this (this would be a great early elementary version):
__ + __ = __
__ - __ = __
__ + __ + __ = __
__ - __ - __ = __
Your student might not be able to fill the entire framework because the cards are drawn randomly, but that's the nature of the activity. Encourage them to use as many cards as possible.
You can repeat this as long as your student is willing to do it. Even better, you can adjust both the equations and the rules to practice different types of problems.
For example, you have to decide what to do about the ace and face cards. I would suggest making the ace a one and the face cards all equal to 10. You can have all of the cards be positive, or make black cards positive and red cards negative. You can increase or decrease both the amount of cards and equations you ask them to fill in. You can also change the type of problem (add multiplication or division).
Here's a much more challenging version of this activity: Increase the square to 25 cards, but create a framework of three addition equations with fractions. Your student has to use the cards to fill in both the numerator and denominator, and while they might take the easy road and use a common denominator, some students will take the challenge of making correct equations without them.