This is a calculator that I have developed for my Algebra students to be able to get instant feedback on their abilities to correctly do the following things when it comes to quadratic equations and functions:
1. Calculate the axis of symmetry.
2. Calculate the maximum output value.
3. Identify if the function will have a maximum or minimum output.
4. Graph quadratic functions.
5. Identify the y-intercept of the function.
6. Calculate the roots of the function.
7. Correctly calculate and create an input and output table of values that satisfy the function.
Here is how it works. All you need to do is enter the coefficients of the function into the white cells. Once the coefficients are entered, the function is automatically graphed and everything above is automatically generated as long as inputs are stuck into the table. I give my students this calculator in the form of Google Sheets and I'm totally fine with you doing this for your students as well (just email me if you would like the google sheet shared with you so you can make a copy and share it with your students). I assign my students to do some problems in regards to quadratics and this allows them to check their work and get feedback on whether or not they are doing things correctly.
The worksheet obviously contains a lot of formulas and my students need to be instructed to not mess with cells other than white cells. The excel spreadsheet that you can download can be protected, but if you share a google sheet with students, protecting the cells isn't possible (that I know of).
I and my students have found it helpful both in the classroom and outside of it. I think it is a pretty cheap way to provide a pretty powerful calculator to all your students. Like I said above, I'm OK with you downloading and sharing with your students, but would request that all teachers purchase the license.