The manuscript presents a contribution to the hydrology teaching task and in general to the water education context,  I suppose at the university level.  Overall the airGRteaching appears an interesting approach for the purpose: it is a versatile tool able to model streamflow data at different time scale, integrating different hydrological processes, it has a nice and attractive graphical interface and seems to have a good module to interact with the model component and model parameters (par 3.1.1.) in order to explore their relevance in the modlling phase. I found not really detailed the calibration and validation module. I see from figure 9 that it would be possible for the student to graphically realize what is the impact of parameter calibration in terms of relevant hydrological processes (snowmelt effect in figure 9), but other model features would be interesting to be explored in my opinion. As an example it could be instructive and informative for a student to learn and maybe visually catch how an hydrograph would be shaped by a range of value of  given parameter (eg. an ensamble of shapes of the recession limbs for an ensamble of catchment delay time) and perhaps have a real time exploration of the assessment of the goodness of fit .

Some minor comments in order to improve the paper preparation:

1)In the abstract (line 5) such as at page 4 line 21, I would suggest the authors to introduce what the GR models (class of models) are, maybe with some basic references. I know that sometime later in the paper a good review of the literature is provided, but I believe some basic reference should be given when introducing the GR models at the very start of the manuscript.

2)The legend and the caption in Figure 2 are not really clear to me. Should be improved.

3)I found not really appropriate the example for "4 years of warm-up" period in figure 8. Probably it was mentioned just as an example, but maight be a bit unrealistic.

4)Also in Figure 12 the legend and the caption should be improved.

The manuscript explains the importance of teaching hydrological modeling and the development of an R package capable of teaching and investigating various hydrological parameters. The topic is relevant in hydrology, but the manuscript needs a moderate revision before publishing it to HESS. Please consider my comments below.

1. Introduction: The explanation is too less. May be the authors can provide more explanation.

1.1: Needs to be improved.

1.3: Needs to be improved.

1.4: Needs more explanation on the importance of R in the hydrological sector. Currently, what are the model/calibration packages available in the R environment?

1.5: Needs more explanation on why this package is important?

Section 2 is well explained. The website is informative.

Section 3.2.2: What is the optimization function used for calibrating the model? Needs more explanation here.

Overall, it is a good effort to develop this model, and very useful for hydrological teaching. However, it requires more explanation and simple language to get attraction from the model users.