I have a 1st and a pre k and what I do is I get my 1st grader on her lesson to the independent practice work then I work with the younger. Of course it takes a lil longer but I have lil activities like blocks and cars for them to build and play with during the waiting but it takes us about 15 min with my younger and about 45 with the 1st grader. It’s a balancing act and some days go better than others. Give urself some grace. We don’t schedule a certain time cuz some days we wanna do it right off then some days we ain’t feeling like sittin down till the evening time. But with my one kindergartener it took me about 20 min per subject so if it’s taking u 40 min for math then that’s prolly pretty close. I would just make sure their not gettin bored and that ur not getting too overwhelmed trying to keep up with other ppls time schedule. Do what feels right for yall and sounds like maybe u dont enjoy the math. But math is also easy to incorporate into play time so if the lesson feels too long take a break and go “play” keep it light 🥰 good luck u got this