For SLE 15 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Education/SLE_15/Education.repo
zypper refresh
zypper install xlogo
For SLE 12 SP5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Education/SLE_12_SP5/Education.repo
zypper refresh
zypper install xlogo
For SLE 11 SP4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/Education/SLE_11_SP4/Education.repo
zypper refresh
zypper install xlogo